INTERNET - through centuries the way of inter-human communication was limited to written messages - from letter delivered by the post and messengers to books. Finally, in 20th century it came to the invention and extension of a few groundbreaking inventions, such as telephones, radio communication and television. The real revolution came during a sudden evolution of computer technology at the end of 20th century and during popularization of PCs and notebooks. In 1969 the American Defense Department worked out the system connecting single PCs in one, big net. 20 years later this idea was used in joining PCs of the citizens - this big "web" became to be known as Internet. This word is an abbreviation of an american term International Network.Most of the information in Internet is published in the form of so called websites, joing together to make bigger portals (thematic or of any company, etc), which are put on the Internet by special computers with huge counting power and not smaller memory - they are called net servers. All the information in the form of websites, electronically connected by servers is called WWW (World Wide Web). Nowadays, Internet is an ocean of information and is used by millions of people around the world. Communication through the net is quite simple - it doesn''t need any advanced knowledge of computers. Single users may communicate with each other in a convenient way thanks to the electronic mail, shortly called e-mail. A basic set used to communicate through e-mails is a PC with modem, stationery telephone and a programme maintaining internet connection. Every user has their own address, which is used to get and send messages. This form of communication allows sending graphical and text messages in the form of files shown on the screen. Thanks to this system we can send a messages around the world in a few seconds for the cost of local phone call.