Modems enable computers to be connected so they can exchange information. Both computers must have a modem. One computer sends its information to the modem which converts it into sound and sends the sound over the telephone. The other computer's modem listens to the sound, converts it back into computer data, and sends it to its computer. Thus, even though sound is moving across the telephone wire, the computers on each end of the connection only see computer data.
Modems can transmit computer information around the world.
People use them to see information on other computers, to get free programs which are stored on other computers, and to send messages to other people. Those people can use their computers and modems to get their messages. A 2,400-baud modem can send about 50 words a second, while a 28,800 baud modem can send more than 500 words each second.