The Internet In 1969, the US Department of Defence started a project to allow researchers and military personnel to communicate with each other in an emergency. The project was called ARPAnet and it is the foundation of the Internet. So what is "the Internet"? The Internet is a gigantic collection of millions of computers, all linked together on a computer network. The network allows all of the computers to communicate with one another. A home computer may be linked to the Internet using a phone-line modem, DSL or cable or wireless modem that talks to an Internet service provider (ISP). A computer in a school will usually have a network interface card (NIC) that directly connects it to a local area network (LAN) inside the school. The school can then connect its LAN to an ISP using a high-speed phone line like a T1 line. A T1 line can handle approximately 1.5 million bits per second, while a normal phone line using a modem can typically handle 30,000 to 50,000 bits per second. Modem (from modulator-demodulator) is a device that modulates an an*log carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Internet service providers (ISPs) then connect to larger ISPs, and the largest ISPs maintain fibre-optic "backbones" for an entire nation or region. The backbone is the main cabling of a network that all of the segments connect to. Backbones around the world are connected through fibre-optic lines, undersea cables or satellite links. They can transfer huge amounts of data very quickly. In this way, every computer on the Internet is connected to every other computer on the Internet.