A bulletin board system or BBS is a computer system running software that allows users to dial into the system over phone lines and perform functions such as downloading software and data, uploading data, reading news, and exchanging messages with other users. Most BBSs were run as a hobby by the "sysop" (system operator) and not for commercial purposes.

Bulletin board systems were in many ways a precursor to the modern form of the World Wide Web and other aspects of the Internet. BBSs were more of a social phenomenon and were used for meeting people and having discussions in message boards. The BBS was also a local phenomenon, as one had to dial into a BBS with a phone line and would have to pay long distance charges for a BBS out of the local area. Thus, many of a BBS's users lived in the same area and it was common for a BBS to hold a BBS Meet, where all of the users would gather and meet face to face.

A typical BBS has:

• A computer
• One or more modems
• One or more phone lines
• A BBS software package
• A sysop - system operator

The BBS software usually provided:

• Login screen
• Welcome screen
• One or more message bases
• File download area
• File upload area (sometimes)
• Online games (usually single player or only a single active player at a given time)
• A doorway to 3rd party online games
• Usage auditing capabilities
• Multi-user chat (more common in later multi-line BBSs)

BBSs grew in popularity from the late 1970s to the early 1990s and have greatly declined in popularity with the rise of the Internet in the middle/late 1990s. BBSs were so popular that a major monthly magazine "Computer Shopper" would carry a list of BBSs along with a brief abstract of each offering.

BBSs were painfully slow at the original 110 and 300 baud modems used, but speed was acceptable at with 1200 baud modems and faster ones, which led to their first increase in popularity. Most of the information was presented in ASCII with ANSI escape codes, though some did offer graphics, particularly after the rise in popularity of the GIF image format. Such use of graphics taxed available bandwidth, so there was considerable demand for faster modems, going from 1200 to 2400, 9600, 14400, 28800, and finally 57600 baud (close to the theoretical limit of what a standard phone line can carry).

Before commercial Internet access became common, networks of BBSs provided regional and international e-mail and message bases. Some even provided gateways by which members could send/receive e-mail to/from the Internet. Fairly elaborate schemes allowed users to download binary files, search gopherspace, and interact with distant programs, all using plaintext e-mail. Most BBS networks were not linked in realtime. Instead, each would dial up the next in line, and/or a regional hub, at preset intervals to exchange files. The largest BBS network was Fidonet, which is still widely used outside of the United States.

Much of the "Shareware" and "Free software" movements were started via sharing software through BBSs. A notable example was Phil Katz's PKARC (and later PKZIP). Also Wolfenstein 3d and Doom from ID Software. And many Apogee games.

See also:

• ANSI escape code
• BBS door games -- is there a better term for this? (No, that's what they were called)
• Fido and Fidonet