With the rapid development of science and technology, communication methods of people have changed a lot. In the long history of the past, people communicated with people who were far from them only by letters, which took a very long time to get the message. In the late 19thcentury, telephone was invented, but it was not widely used. Letter is still the main method. Later, telegraph came into being and was popular, which was much faster than letter, bringing great convenience to people. As time goes by, telephones become increasingly widely used. Now, the phones has been developed as mobile phone, fixed telephone, Internet telephone and other categories, being an essential communication tools in modern information society. In addition, network communication is popular as well. A great number of people communicate with others on the Internet, such as the chat room, bbs, MSN and so on. People can make video calls that not only can hear the sound, but also can see the people you talk to. In short, there are various communication methods in modern world, which bring great convenience to people
when men began to like together in small communities, they it was necessary to find ways of sending messages from one community to another.
even in earliest times there were several different ways this could be done. really rapid communication was not possible until electricity was put to work. in 1844 the first electric telegraph was constructed. thirty years later the telephone was invented. soon a whole succession of inventions was produced: the wireless telegraph and the radio, the motion picture, and television.
earth satellites today bring valuable information almost instantaneously to our homes by means of electrical signals.