Dial-up Internet access

Dial-up Internet access connects a computer to an Internet service provider by dialing a telephone number over a modem and a telephone line.

Dial-up modem: A device that modulates and demodulates signals to transmit digital data over an analog telephone line. It converts computer data into signals that can travel through the phone network.
Frequency-shift keying: A digital modulation method that encodes data by shifting a carrier between discrete frequencies. Early telephone modems used frequency changes to represent digital data.
Bulletin board system: A computer system that users access remotely to exchange messages, files, and other information. Dial-up connections let home users call local boards to exchange messages and files.
Digital subscriber line: A broadband technology that transmits digital data over copper telephone lines while permitting simultaneous voice service. DSL uses the same wiring but avoids dial-up's call-by-call connection and voice-line lockout.
Broadband: Internet access technologies that provide substantially higher data rates than traditional narrowband connections. Broadband displaced dial-up by keeping connections active and greatly increasing capacity.
Point-to-Point Protocol: A data-link protocol that establishes direct connections between two network nodes. After dialing, many providers used it to authenticate subscribers and carry network traffic.
Quadrature amplitude modulation: A modulation method that encodes data in changes to a carrier's amplitude and phase. Later dial-up modems packed more information into each telephone-line signal.
America Online: An American online service that provided subscribers with communication, information, and Internet access. Its access software and busy modem banks made dial-up a familiar route online.
Cable Internet access: Broadband Internet access delivered over cable television networks. Cable offered much higher speeds without occupying a telephone call.
Always-on connection: A network connection that remains available without requiring a user to establish each session manually. Dial-up's need to call and disconnect made continuous online presence impractical.

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