The ring-ring of the telephone is one of the most familiar sounds we hear every day. It lets you know that someone wants to talk to you.When 
your friend dials your number, his call is connected to your phone by the telephone exchange. Telephone calls used to be connected by hands with an operator asking the caller which number he wanted, and then plugging in the correct wire. Today, of course, computers do all this automatically
In a telephone, our speech is changed into electrical signals. These signals travel through wires, or optical cables that carry them in the form of 
light. The signals can also travel through the air as radio waves, using satellites or antennas. To make a call, you must dial a series of numbers on your telephone. Once the call is connected, the microphone and loudspeaker in the receiver of the phone allows users to talk to each other. The microphone in the mouthpiece produces electrical signals that travel through the wires, or as radio waves. The loudspeaker in the earpiece turns these signals into sounds again
Indeed it does! Computer language is, in fact, a language made up only of numbers.The names of some computer languages are BASIC, 
COBOL and FORTRAN. These languages teach a computer to perform different functions. The person who writes the instruction in a language that the computer can understand is called a programmer
People who ‘surf’ the internet use a lot of special symbols and terms. Some are needed for technical reasons. Others are used to make
communication faster and more fun!Some commonly used terms are ‘surf’ which means casually looking through different site, and of course ‘www’ which means ‘world wide web’. In internet language short forms are accepted like ‘4’ for ‘for’ or ‘u’ for ‘you’
Radio was a technological revolution that changed forever the way we lived our lives. Its invention gave us a whole new medium of getting 
both information and entertainment. News broadcasts, music programmes, variety shows, serials… radio offer us a dazzling variety of ways with which to keep abreast of what is happening in the world, and also to enjoy ourselves. Some radio stations like the BBC and Voice of America transmit around the globe. There are also smaller radio stations that broadcast to a local area. Radio also changed the way we communicate. Two way radios help people like ambulance drivers to communicate with hospitals. Policemen use radios to keep in touch, and pilots use them while in the air and to fly safely in and out of airports. Children in Australia are sometimes taught by two way radios, because they live so far from any school. When man landed on the moon, the words that he spoke could be heard on our radios almost immediately… that is the magic of radio!
We know that Marconi was the first person to build a machine that could produce radio waves by making a powerful electric spark. His radio
set could send messages, but the first radio broadcast occurred on Christmas Eve in 1906, and was made by Reginald Fessenden, a Canadian engineer, from Massachusetts in US. Wireless operators on ships at sea were the first people to hear this broadcast. They were amazed to hear a human voice coming from their instruments as someone spoke. Then a women’s voice rose in song! Many of them called their officers to come and listen, and soon, the wireless rooms were crowded. Next, someone was heard reading a poem. Then there was a violin solo… and then a man made a speech In this first broadcast, Fessenden himself played ‘Holy Night, Silent Night’ on the violin. He also read Christmas story from the Bible (Book of Luke) and played a phonograph recording of Handle’s ‘Largo’. It was truly a Christmas Eve to remember!
Phone lines are not used only for conversations. If you have a videophone, you can actually see who you are talking to, as the phone lines 
are used for faxes through which you can send pictures, photos, and letters. Computers also use phone lines for an Internet connection, with which you can browse and chat for hours!
Handling of mail often exposes postal workers to dust, especially when the mail bags are opened. Sometimes, dangerous chemicals may be split, and 
there are also electrical hazards that workers have to face. So postal systems have always been interested in mechanizing post offices. Between World War 1 and II, many postal systems introduced conveyor belts to move mail between handling points. The letter sorting office at Mount Pleasant in London was one of the most highly mechanized in the world Gradually, machines were introduced to prepare mail, and sort small letters from the bigger ones. There were also machines to stamp the date on letters and to put them neatly into sacks In modern, mechanized sorting systems, workers sit at a keyboard while letters are mechanically passed in front of them. Approximately fifty to sixty letters each minute are processed by the operator. Based upon the code entered by the operator, the letters are segregated into different bins, and then removed, bundled and dispatched by the postal workers
Only one country is permitted to issue postage stamps without including their country’s name. This is Great Britain. It was the first country to issue postage stamps in 1840. In place of its country’s name, Britain is allowed to include an image of its ruling monarch.
As postal systems developed, and the volume of mail they handled increased, many problems cropped up. To begin with, the cost of transport 
was high, and it was also difficult to calculate the exact cost of letters sent to other countries.Delivery was often slow, and this resulted in people using other means to send their messages. Many illegal postal services sprang up, causing financial losses to official postal systems. Gradually, these problems were overcome. The introduction of the postage stamp by Henry Bishop did away with uncertainties regarding that should pay the cost, and regularized charges. Since the day and month were also printed on the steps, unnecessary delays could be checked Today, we have speed post which guarantees 24 hours delivery to most places. We have come a long way indeed from the days when it sometimes took weeks for an urgent letter to reach us!
In 1680, a merchant named William Dockwra organized the London Penny Post, which delivered mail anywhere in London for just one penny.
He also introduced the practice of postmarking letters to indicate when and where they had been posted.The penny post had seven post offices, and 400 collection boxes throughout London. Letters were delivered ten or twelve times a day in the centre of London, and four or five times in the suburbs. However, the penny post became so successful that the government took control of the operation in 1682, and absorbed it into the Post Office. From then on, charges gradually increased, and letters were no longer delivered for a penny.
Today, the postman delivers your letters to your doorstep, but it was not always like that. In the early part of the 19th century, envelopes were 
not used. Instead, a letter was folded and the address placed on the outside of the sheet. The customer had to take a letter to the post office to mail it, and the addressee had to pick up the letter at the post office. In big cities in the USA, mail would be delivered home if you paid the carrier. In 1863, free city delivery was instituted in 49 of the largest cities in the USA. By 1890, 454 post offices were delivering mail to residents of United States cities. It was not until the turn of the century, however, that free delivery came to farmers and other rural residents
You might have seen your parents give a letter to someone who is going abroad so that they can pass it on to your relative who lives there. 
Well, in earlier times, when there were no postal services, this was how letters and messages were sent. This method of using travelers to deliver messages to other places developed into a system known as post riders.So we can say post riders were a horse and rider postal delivery system that existed at various times and various places throughout history. Post riders collected and delivered mail over the course of their route, meeting with other riders at scheduled times and scheduled places. Letters and parcels would be exchanged and forwarded to the next place by the riders. In this way, messages could pass a considerable distance
Airmail is mail that is transported by aircraft. It arrives more quickly than mail that comes by road or ship, which is called surface mail.
Airmail also costs more to send. If you want to send an urgent letter overseas, you have to send it by airmail. If you send it by ship, it could take weeks. In the case of airmail, the letter would reach its destination in days.
Today, the postman delivers letters to every home. In the past though, the post was a privilege enjoyed only by kings and emperors. They used
runners to carry messages to other rulers and to their commanders during times of war. A king would have a message inscribed on a clay tile and send a runner to take it to anotherHowever, the ancient Egyptians though did have a kind of postal system and so did the ancient Chinese. The early postal systems depended upon post houses that served the carriers of messages or mounted messengers. The Romans created the most highly developed and dependable system in the ancient world. This system could deliver messages 270 kilometers in 24 hours