People imagine telecommunications means communications using only electrical or electronic technology, but that isn't so.
'Tele' is a Greek word meaning 'far off' so the purest definition is 'communications over a distance'.
In other words, telecommunications means anything that involves sending messages or signals.
Messages and signals are essential components of telecommunications. But what is the difference?
A message is the product of communication, in other words the information we need to convey. It may be audible (a telephone call or voicemail message for instance) or visual (an e-mail, a telegram or a text on your mobile). These are all examples of messages.
A signal is the electrical activity that sends our message or the product of our communication.
To turn signals into messages you need two more components - a 'transmission protocol' and a code.
The process of telecommunications can be separated into two elements: 'the bearer' and 'the intelligence' it carries.
The bearer element is the one that carries the message. This is the system that carries signals from one place to another. You could see it as the electrical equivalent of the postal system, only using wires, optical fibres or radio waves instead of postmen and mail vans.
Intelligence or information is what the system carries, just like the news within a letter or the pictures in a book delivered by mail. Various methods are used to convert these messages into electrical signals and back again into a form understandable to the recipient.
When the postman arrives with a packet, he's carrying a message. When he knocks on the door, that's the signal telling you there's a message waiting.
The protocol is the understanding that links sender and receiver - you hear the knock or bell so you open the door.
In telecommunications the 'protocol' is the particular set of 'understandings' for exchanging information between two devices in a communications network. Protocols provide a set of rules or procedures that determine the format and timing of information transmission.
Look at it this way: you could put two people at random at either end of a telephone line. But unless they could both speak the same language and agreed not to talk until the other had finished, no meaningful communication would be achieved.
Being able to send a signal is one thing - but turning that signal into a message is quite another.
Signals are 'dumb' - they only tell you someone is there at the other end of the line or link. Making signals talk requires one more component - a code.
A code defines the pulse, tone, flag, semaphore or light patterns that will be transmitted - so that each pattern can be recognised as a separate component.
Then it assigns each pattern to a letter, number, word or phrase that makes sense to us.
Code applies human intelligence to the dumb signal to allow it to communicate a message. So in Morse code you would realise that dot dot dot dash dash dash dot dot dot actually means SOS, which in turn signifies an urgent distress message.
