My Tech Tips

​I shall not go into how you set up and insert a signature block but the help page of your email software package will be able to instruct you on this.
 
Using Rules
Another feature in all email packages is the ability to create what is called a ‘Rule’ (sometimes referred to as a ‘Filter’). A Rule can be very useful if you want to apply a certain action or sequence of actions to a given message you have received. The standard format for a rule is something like ‘If X occurs then Do Y’. This is best understood by looking at an example of the rule dialogue box (this is from Apple Mail on my iMac).

​Clicking on any of these arrows opens up a choice. Here is a screen shot of the choices when clicking on the box currently saying From (A):
​

​Here is a screen shot of the choices under the Perform the following actions box currently saying Move Message (B):
​

Here is a screen shot of the choices under the main Conditions box currently saying Contains(C)
​

Although you do NOT need to worry about trying to understand it, this last picture is included to show that delving deep into the email header can enable you to find out if the sender is legitimate or not. It is taken from a live example from the internet so actual user's name has been obscured). The wording of the header detail is difficult to read but the key parts are shown by the arrows.
​

In the previous article I described the basics of emails; how they work; the difference between webmail and desktop mail; and a little about email software packages. Armed with that knowledge you can make perfectly good use of this popular facility. However, there is actually a lot more to emails than first meets the eye and many ways that you can improve the way you use them. If you would like to know more then this article is for you.
 
Here are the topics I shall cover: 

• Types of Email Address
• Creating and using Address Groups
• Email Preferences
• Managing your Inbox
• Sorting your viewing page

 
Types of Email Address
We are probably all familiar with the usual email form that appears when we click to write a new email. The top of this form looks like this:

​The To: box and Subject: are self-explanatory but you may not know what the others mean.  Cc: stands for Carbon Copy and is just like an old typewriter letter where one or more pieces of carbon paper interspersed with blank paper enables you to create copies.  Bcc: stands for Blind Carbon Copy.   What is the difference between the two in email terms?  Anyone whose address is in the Cc: box will receive a copy of the message as well as the person(s) in the To: box. Important point: All the recipients included in the To: and Cc: boxes will be able to see who else has received the email.  This may not be appropriate so, if you want one or more recipients to be invisible to others, you should put the addresses of these (invisible) recipients in the Bcc: box. Not only will they be invisible to anyone in the To: or Cc: boxes but they will also be invisible to anyone else in the Bcc: box.
Note that you can still have addresses in the To: and Cc: boxes because there might be someone that you DO wish to let know that you have sent the email to the others shown.
Sometimes you might want to send an email to a whole group of people but not want ANY of them to know who else has received the email.  In this case you can put your own email address in the To: box and everyone else in the Bcc: box (with no address in the Cc: box).
 
The Reply to: box (where it is set up to appear) will either have your own email address in or you can insert an alternative email address if you want replies sent to a different address. Any email received will always show a From: box and this will be the address of the sender. However, there might be instances where you wish replies to be sent elsewhere – either to someone else who is monitoring replies or to an alternative email address of your own so that you can separate all the replies to a particular message.
 
There should always be something in the Subject: box. If not, you will get a message pop up saying that there is no subject and asking if you still want to send it. You can do so (without a subject) but be aware that many email providers flag up messages without subject lines as potential spam or hoax emails.
 
Creating and Using Address Groups
If you have just a few people to send emails to it is easy enough to put their email addresses in one by one.  Usually, if you have emailed them before, their email address will pop up as soon as you start typing their name. 

Sometimes however, such as if you are managing a society or group of people, you might have a large number of people to whom you want to send the same email. Let’s say you have 50 people in the society. You could type each of their addresses into the To: box but this would take forever – especially if you are likely to send another message soon after to the same people. We get around this by creating Groups in our address book. Thus a group called (for example) “My Society” might have 50 names in it.  Once you have created the group it is a simple matter of typing in “My Society” in the To: box and all the names will suddenly appear. Don’t forget to use the Cc: and Bcc: boxes in the same way.

Note that there is a limit to the number of addresses that email packages will let you send at any one time and this can be up to 80-100. There are other types of programme to use if you regularly go beyond this.

I shall not go into the subject of how to create groups as this varies considerably depending on the email package you are using. If you want to know how to do it, use Google and type in your email package name and ask how to create email groups.
 
Email Preferences
All computer programmes have the facility to adjust settings to suit your own way of working. These changes are accessed by finding the section of the programme called ‘Preferences’ (sometimes ‘Customise’ or 'Options'). Email programmes are no different with the exception that there are often a lot of potential changes you can make. I don’t intend to go into details on this here because not only are there so many different variations but each email software package will have its own set of permissible changes.  However, here is a list of the kind of changes you can make (there will be many more than shown here):

• Ways to view messages (i.e. show to the right or below the message list).
• Font, size and colour of text in the messages.
• Number of lines to preview in the home page.
• Check for messages automatically or not (Push or Pull).
• Play a sound when a message arrives.
• Action after a message is read (file, delete, implement a rule or nothing).
• What to do with junk mail and spam.
• Whether to include a sender’s message when replying to him/her.
• Whether to include a signature block (See later).
• Whether to apply any rules (See later).

All programmes (including email ones) come with a number of these settings already set as the default. The default settings are based on what the majority of users will tend to use. You don’t have to make any changes if you don’t want to. As you get more experienced with using email you may find that you prefer to show things slightly differently and the Preferences option is where to go. All changes are reversible.
 
Managing your Inbox
Depending on how many emails you receive and send you may be happy just to let your inbox (and sent messages box) grow and grow. There are several reasons why this is not such a good idea. First, before long you will find that you have to scroll down the screen a lot to find an older message. Second, it keeps messages jumbled up together without any separation between different topics (such as shopping, social, outings, bills etc). Third, it makes it difficult to quickly find all messages on a specific topic or at a given date.
 
For these reasons it is preferable to create separate folders to hold all emails of a particular subject or from a particular person or persons.   There is no limit to the number of folders you can create and each folder can have sub-folders. Here is an example taken from my own email package. You can see that I create what I call Archive folders and allocate one to each year. Within that year I have sub-folders for messages In and messages Sent.  All messages will go into the appropriate folder unless I wish to keep a separate folder for the more numerous emails. (Guess who uses Amazon quite a lot!)

​Where to keep these folders? If you remember the earlier article where I described the difference between desktop mail and webmail, you will know that you can keep these messages on your desktop/laptop or in the internet on your webmail package. For both methods you need to take specific action to MOVE selected messages into the appropriate folder. (Note that you must create the folder first). You can do this either by manually selecting one or more messages and then dragging them to the correct folder; or you can create a Rule that must be followed under specific circumstances. (More about this in my next article).
Remember that there is no need to delete every message as soon as you have read it. Emails don’t take up that much space and, if you have them in separate archive folders, you can always save these to external storage if you are worried about space.
 
Sorting your viewing page
Quite often people ring me to say that they have “lost all their emails”. Invariably the reason is that they have inadvertently altered the order in which they are displayed. In fact it is very easy to do and, fortunately, just as easy to correct it. In the box where all your emails are displayed will be something like this which is my inbox on Thunderbird Desktop software (different email packages may vary):

​On the left-hand side will be the list of your email folders. (If this is not present you can make it visible by clicking on the ‘View’ option in the menu and clicking “Show Folders’). At the top of this column will be the name of the email account followed by the pre-assigned folders for the usual boxes. Note that, next to my email address there is a downward facing arrow and, similarly, next to the faint heading ’(Gmail)’. These downward facing arrows are important and feature a lot in email displays (and other software packages also). Clicking on the arrows in this column will cause the mailbox headings (Inbox, Deleted) to collapse and all you will see will be the single headings showing your email account and the Gmail title.  The arrow will change to a right-facing one > which is the indication that the folders beneath it have collapsed.  Clicking the arrow again will restore the folders.
​
Looking on the main panel you will see a range of headings thus (again they will very according to your email package):
​

​In my example the standard headings are Subject, Correspondents (or Senders) and Date. To the left is a black asterisk * and a paperclip symbol. The asterisk relates to those messages that you have ‘flagged’ as important. In the column below this black asterisk there appear blank asterisks. All items that have been flagged will be filled in with a colour. By clicking on the black asterisk at the top of the column, you can re-arrange ALL the email into order showing either all the flagged (asterisked) messages first or (click again) and they will appear last.  All the other detail related to that email will be correspondingly re-arranged.

Next to the asterisk is the paperclip which symbolises that an email message has an attachment to it (such as when someone send you a photograph attached to their email). Just like the asterisk, clicking on the paper clip will rearrange all the emails into order with all those messages with attachments listed first. Click again and they will be shown last.
 
Now, following the same principle, if you click on any of the other headings all the messages will be rearranged in order. With Subject, one click will put them into alphabetical order A-Z whilst a further click will change them to Z-A.  You may need to scroll up and down to find the messages at the bottom of the rearranged list. With Correspondents or Senders the names of your senders will be re-arranged in alphabetical order A-Z or (another click) Z-A. Similarly, with Date you can sort the emails into Oldest first or Newest first.
 
What usually happens, therefore, when someone tells me they have “lost their emails" is that they will inadvertently have clicked on one of these headings and altered the order in which the emails are displayed.  
 
Summary
I must apologise for the fact that this article is a bit complex. It is difficult to explain the variations between different email packages without going into detail on each one. Therefore I have used a typical package (Thunderbird) to demonstrate the principle. I am not necessarily recommending that you should use it 
 
Look out for the final article on emails in which I shall cover four remaining topics:

• Writing Style
• Using Signatures
• Using Rules
• Hidden Information

​Emails; you either love them or hate them. Personally I love them. The first email facility was actually as long ago as 1979 but this was a fairly restricted academic/scientific venture. A limited consumer capability arrived in 1989 with the sale of Lotus Notes software but it was not until 1996 when the first universal service was started. This was Hotmail. I have used emails since the mid-90s with a variety of different software products. Microsoft’s first email package was Microsoft Mail which was launched in 1991. In 1996 they launched Outlook which was, basically, Hotmail.
 
Today I use Google Mail (now called Gmail) almost exclusively. (As they say on the TV, other email packages are available. This is not an advert for Google!) Gmail was launched on 1 April 1994 and proved not to be an April fool. Since I started using Gmail I have sent and received 70,000 messages. I have got copies of emails before Gmail but many of these are in file formats that are unreadable today without some technical manipulation. In the year 2020 the total number of emails sent and received globally was 306 Billion per day. Yes! Every day. If you think I am an excessive user, my total equates to about only 8 per day.
 
In this article I will try to cover the following:

• How email works.
• The difference between mail on the internet (webmail) and desktop email.
• The range of email packages.
• Some miscellaneous tips and facts.

 
How Email Works 
There is a lot more to an email than just the message you type out on the screen. Think about a traditional letter written by hand. It carries your address and the date you write it and can run to several pages. Sometimes you can add a photograph or a newspaper cutting and clip it to the letter. This then goes into an envelope on which you write the recipient’s address and then affix a stamp. You then post it in a red letter box.
 
An agent (the postman) periodically empties the letter box and the letter goes to the sorting office. Once there sophisticated machinery sorts all the letters and puts them into mail bags – a different bag for each destination.  The mail bags are then sent off to the various receiving sorting offices where they are placed in dedicated pigeon holes corresponding to the delivery postmen’s rounds and eventually arrive at your front door.

​Emails work the same way except that the “envelope” containing all the routing information is hidden from you. (There is a way to see it but I will cover that another time). The email is then posted (sent) to the internet in the same way that you place a letter in a letter box. The full email process is as follows:
 
The letter is written and addressed and when you send it off it goes into your Outbox. The electronic postman (your internet provider) "collects" the messages from the Outbox and sends them to the internet “sorting office”. Here they are routed to the different email providers (like Gmail, Outlook and so on). When they reach the provider they are sorted into each of the individual addressees' “pigeon holes” to await their delivery to the recipient. The recipient’s computer receives the mail sent to it and places it in your Inbox until such time as you can read it.
 
The only difference between the physical and electronic messages is that, with email, all these processes (with the exception of the actual reading of the message) occur instantaneously – the Outbox doesn’t have to wait until it is filled or until a certain collection time arrives. Each individual message is despatched and sent on its way immediately and doesn’t have to be “batched up” with others. Thus emails go winging around the internet every second of the day and night.
 
The email provider (let’s say Gmail) acts as a holding bay. Now – important point - there are two ways in which emails can be sent to your computer. One is called “push” and the other “pull”.   Push acts like the normal postal service and messages are sent to you automatically. Pull, on the other hand, is like a “poste restante” service where the post office holds the letters until you call and ask for them.  In the case of emails it is your computer which requests the “post office” to download the messages to you.
 
Internet Email (Webmail) v. Desktop Email
This next section explains something which often confuses people. The email software that handles your messages enables you to read, reply and store those messages.  But it can do this in two places – either on the internet or on your computer (desktop).
​
Internet Mail (Webmail)
First, again using the Gmail example, you can view all your messages by going to the internet and visiting the site that holds your Gmail. This will be found at https://www.google.co.uk. If you have a Gmail account you will be presented with this screen

​If you click Gmail this will take you to your mail area (if you are already logged into your Google account) or to a Gmail log in screen if not. (If you have never used Gmail before you will be invited to open an account. This is free.) Once logged in you will be presented with a fairly familiar layout showing all your messages – in and out – plus any you have saved.  This email on the internet or web is called Webmail. Many people just use a webmail package and there is nothing wrong with doing that. As an aside, you may wonder what the square of dots is. If you click on this it opens up a list of all the other Google Applications (Apps) that you can use if you have a Google account. We'll look at these another time.
 
Desktop Email
The one drawback to using webmail exclusively is that, if your internet connection goes down, you will be temporarily unable to use email or see your messages. Before the arrival of the ability to share voice and data over telephone lines (read an earlier article here to explain this), it was necessary to dial up to the internet, quickly find and download your messages and then cut the connection so someone could continue to use the telephone for speaking. To be able to read the messages downloaded a software package was required to present them on your computer screen. This was the origin of Desktop Mail. The term we use for such a package is a Client and the store of messages held on the internet is called the Server. The link between the two is called a Client-Server relationship. These terms client and server are used a lot in computing not just with email packages. In fact in earlier, non-politically correct days it wasn’t called Client-Server but Master-Slave and was depicted thus with the master or server obviously being the dominant side.

​Should I use a Client Mail package or Webmail? 
Generally speaking you will tend to select whether to view and manage your mail on the desktop client or on the web depending on which you feel more comfortable with. The main advantage of client-based mail is that you can read any downloaded messages and draft responses even if your computer or device is disconnected from the internet – in other words offline. (Naturally your drafts, which are held in your Outbox, don't get sent until you are back online again). You can also keep a local copy of your emails if you are concerned about the security of leaving them on the web or if your webmail package has a limitation on storage. Webmail on the other hand allows you to access your mail from a separate device to the one where your client software package is sitting. These days we often have several devices (iPad and iPhone) in addition to a desktop or laptop computer.
 
The Range of Email Packages 
Webmail This software comes in two sorts. Each internet service provider (ISP), such as BT, Virgin, Tesco and so on, usually has its own mail service and your subscription to the ISP comes with an email address such as [email protected].  It is perfectly OK to use this but some people prefer to use a different sort of webmail package since they often offer more features. If like me you use BT as an ISP and Gmail as your webmail, when you login to your internet through your provider you can then, instead of looking at the ISP's email package, click to see your chosen webmail. There are many of these webmail packages like Gmail that are independent of ISPs.
Client Mail Packages are numerous and varied and are often unique to the device you are working on. Apple computers for example have Apple Mail; Windows computers have Outlook. However, you can also choose from a whole host of other client packages that, like webmail, are independent of their main provider. There is not enough space to list all the many client packages here but popular ones over time have been Thunderbird, Live Mail, Samsung Mail, Yahoo and Outlook Express. Note that you don’t have to have the same client email as the one you use on the web. It is a fairly simple matter to have your client mail set so that it visits your webmail provider. For example, I use Apple Mail on my desktop and iPad to read and reply to messages but these devices “visit” my Gmail account on the web and download messages accordingly.
 
Some Miscellaneous Tips and Facts
Before closing this article, here are one or two tips and facts about email generally.

1. People worry about “filling up” their computer and tend to delete every message as soon as they have read it.  There are two main reasons why this is unnecessary. First and foremost you never know when you might need to refer to an earlier message. Second, by a very rough calculation 250,000 emails (far more than I have used over many years) would consume about 25GB (Gigabytes) of storage. On today’s computers this is a very small amount of the inbuilt storage. On the internet, however, the cost of 25GB of storage could start to mount up. If you are still worried about using up space on your computer you can always invest in extra, external storage (a hard drive) to hold your mail archive.

2. Attachments - anything you "pin" to the email message like a photo, video or document) can add considerably to the overall size of your email and, as a result, its storage requirement. Most email providers limit the size of attachments for this reason and also because they take longer to transmit.
 
3. Something like 50% of all emails are useless. They consist of spam, hoaxes, advertisements and replies copied out unnecessarily to recipients other than the main addressee of the original email. Naturally, you can delete these permanently and there is no need to keep them at all.
 
4. What do other languages call the @ sign? In fact the English “at” is about the most boring of all. Very common references are made to a monkey’s tail, an elephant’s trunk and a snail. In German it is called Affenschwanz meaning ‘monkey’s tail’; in Hungarian it is Kukac which means ‘worm’ or ‘maggot’; in Norwegian it is alfacroll meaning ‘curly alpha’; and in Vietnam is it called acong (‘bent A’) in the North whereas it is amoc (‘hooked A’) in the South.
 
5. Once an email has been sent there is NO WAY you can unsend it. Don't be tempted by any package that offers a Recall facility. All this does is send a request to the recipient(s) asking them to delete the earlier email. This merely draws attention to the original error and advertises your mistake to other recipients. Accidentally pressing Send for an email that you specifically didn’t want to send is about as heart-stopping as clicking shut the front door and realising you haven't got the key! 

In my previous article I wrote about Understanding Computer Communications (Read it here). I covered the history of communication and how today’s computers communicate with the user, each other and the outside world. I focused mostly on the use of wires and cables for the transmission of data. But the common terminology for exchanging information with computers is 'Networking'. Rather confusingly, networking can be both wired or wire-less. This article explains all about network connections. Here are some terms that I will cover: Local Area and Wide Area Networks (LANs and WANs), Ethernet, Wi-Fi, Bluetooth, Mobile, Terrestrial, and Satellite.
 
Wired Networks (LANs and WANs)
When we talk of a network we refer to an arrangement whereby one or more computers can be linked together to exchange data. This can be within one’s home or office (the Local Area Network or LAN) or between different buildings and departments of a business (the Wide Area Network or WAN [sometimes called a Corporate Network]). Of course, we have already met one network called the Internet(work) which is really a global network for information exchange.
 
Local Area Networks (LANs) can be established by connecting the computer(s) within the home or office using wires or wireless signals.  When we use wires we use a form of cabling called Ethernet. Ethernet cables can be any length and there is usually little or no degradation of signal over reasonable distances. Ethernet cables are about the thickness of a normal electrical appliance cable. They consist of a number of separate wires which are bundled together and encased in a plastic outer sheath. Typically they run along skirting boards and although they can be visually distracting they can blend in well especially if you choose an appropriate colour cable. Most people will be familiar with this ethernet cable since one is always included in the box when you take delivery of an internet hub or router. Here is a picture of an Ethernet Cable. 

​You will notice that there is a different type of plug at each end of the cable and this demands a special socket or port to connect to at its destination. For the technically curious this plug is called an RJ45 (which stands for Registered Jack 45).The ‘destination’ it plugs into might be the back of your computer, a port on your internet hub/router, or even a junction box for sharing the network between more than one device. Here is a picture of the LAN socket or port with its cable. Look for it on the back of your computer or hub.

​If you ever have the luxury of having a new house built it makes sense to get the whole house cabled for ethernet with appropriate sockets in each room. This way, the cabling can be hidden behind plasterwork or walls in just the same way that a ring main electric cable is laid out and hidden when building a house. Here is a picture of a typical face plate that might be built into a wall to provide a network connection point.  Increasingly these are being combined with three pin plug sockets and USB charging points. The ethernet socket usually sits behind a small shutter that has to be lifted up to insert the connecting cable. This shutter prevents the ingress of dirt and dust. You will be familiar with these shutters on telephone points. Interestingly, the standard telephone plug is called an RJ11 (Registered Jack 11) and is smaller than the ethernet plug.

​Wide Area Networks (WANs) are where different parts of an organisation are linked together over distances. A business with, for example, a headquarters and a number of regional offices each with its own LAN, might have a WAN that connects all the regional LANs together. Thus regional businesses can operate by themselves over their LAN but communicate data to other regions and to the Head Office by means of the WAN. How these separate LANs are combined is outside the scope of this article but it requires some kind of “junction box” often called an access point. The "highway" for connecting LANs and WANs together is actually the internet. However, the difference is that the LAN/WAN network is private to the organisation and will have safeguards to maintain that privacy. Other organisations that use WANs are Universities, academic institutions, Local Government and Voluntary Services.
 
Wireless Networks
Now let me look at networking without wires - literally Wireless. We have become accustomed to the term Wi-Fi. Knowing that the musical HiFi stands for High Fidelity, it is commonly thought that the Wi-Fi means Wireless Fidelity. This is actually untrue; Wi-Fi doesn’t stand for anything. It is an official trademark of the Wi-Fi Alliance. When looking for a term to describe wireless connectivity they thought that HiFi had a catchy ring to it and imitated it with Wi-Fi.  Note that the correct term is Wi-Fi not WIFI or wifi.
 
All forms of wireless communication require the presence of a transmitter and a receiver. Any device connected to a wireless network has to have the ability to transmit and receive. Depending on the distance between the sender (transmitter) and the device being sent to (receiver) there is often a need for the signal to be boosted on its journey. This is called relay and, like an athletics relay race, has one device in the chain taking hold of the message and carrying (relaying) it to the next recipient and so on.  To understand this concept, think of mobile phones and televisions. The former requires a network of masts (relays) and the latter the presence of large transmitters (relays) usually sited on prominent hilltops.  
 
It is the distance between devices (or between the intermediate relays) that determines the kind of wireless technology to be used.  Here is a brief rundown of the technologies based on distance:
 
Near Field Communication (NFC) This is a common feature of point of sale payment systems using credits/debit cards and mobile phones. The message (card details) are transmitted between the card/phone and the device used by the shop or individual to take the payment.  A receipt message is transmitted back to the card/phone. The maximum distance is about 4cm.
​
Bluetooth This technology is used to transmit data at high frequencies over short distances – typically up to 10m but (with higher-powered devices) up to 100m. The technology takes its name from the 10th Century second king of Denmark, King Harald Bluetooth. He was famous for uniting Scandinavia and serves as a metaphor for our uniting computers and devices.  A lesser-known fact is that the blue symbol we use for the Bluetooth icon is actually the initials of Harald Bluetooth in Scandinavian runic script.

Common uses of Bluetooth are for connecting devices such as keyboards, mice and touch pads to their parent computer. Bluetooth is a common feature used in cars for connecting one’s mobile phone to the vehicle’s own computer.  The act of uniting the two devices is called “pairing”.
 
Wi-Fi Perhaps the most regularly-used and recognised form of wireless connection in the home is Wi-Fi. Depending on the inbuilt technology being used and the radio frequency it operates at, Wi-Fi can connect over distances up to 50m indoors. Older devices managed much less. Wi-Fi is typically used for creating a Local Area Network in the home or office. Devices connecting to the network (such as printers, scanners and other computers) do not have to be in line of sight of other devices but have to be within the range of the Wi-Fi transmission frequency.  Where the distance is too much to get a constant signal it is common to use a repeater or extender to act as a relay to other parts of the house.

​​Mobile Communications The next kind of wireless communication is the mobile phone network. Here a more powerful transmitter in the phone or device is able to connect over much greater distances provided that it is within the range of one of the mobile network company’s transmitters (or masts).  Line of sight plays an important part in being able to connect as does the sort of technology being used by the network.  Coming into more regular use is what is called 5G mobile (where 5G stands for 5th Generation). A 5G network is capable of sending signals over much greater distances than earlier generations.  Using the same metaphor of the relay race, mobile network transmitters/masts are situated in a carefully designed geographical spread – each mast counting as a cell which, in conjunction with the other masts in the area creates a cellular network. This is why mobile phones (especially in the US) are called Cell phones.  You will hear an American asking for your “Cell” when he wants your mobile number. Here is a depiction of a mobile network cellular structure (photo courtesy of Rhode & Schwarz):

​The key thing about mobile/cellular networks is that the pathway around the network is switchable – often immediately and without interruption – if one adjacent cell cannot be connected to or is busy. Thus the route a message takes can vary and can be quite circuitous. This gives the network survivability should one cell or group of cells go out of service. The origins of the internet are based on a cell network that was developed in the early 1970s and was intended to be survivable in the event of a major war. The network could carry on working provided a route round the network could be found.
 
Terrestrial Communication  As previously mentioned, Television and Radio programmes are carried across the airwaves by means of transmitting stations. These are much more powerful than mobile phone masts and thus fewer are needed to cover large areas.  The receiver in this instance is the aerial on the roof of your house or in the attic or built in to the television itself. (Joke: Someone was puzzling over a TV set in a shop that said on the box ‘Built In Antenna’. He said to the salesman that he was hoping to get one built in the UK.)
 
Satellite Of course, more and more television programmes are being broadcast by satellite of which Sky is one of the foremost providers. These broadcasts are still wireless even though you can now get cable TV.  Just like terrestrial television, satellite television requires a receiver which is the dish affixed to the outside of the house. Since, like most wireless transmission, line of sight is a necessary factor, the transmitting satellite is what is called geo-stationary, which means that its position remains constant regardless of the rotation of the earth.
 
A Final Word about Line of Sight