A bulletin board system or BBS (also called Computer Bulletin Board Service, CBBS) is a computer server running software that allows users to connect to the system using a terminal program. Once logged in, the user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging messages with other users through public message boards and sometimes via direct chatting.

<communications, application> (BBS, bboard /bee'bord/, message board, forum; plural: BBSes) A computer and associated software which typically provides an electronic message database where people can log in and leave messages. Messages are typically split into topic groups similar to the newsgroups on Usenet (which is like a distributed BBS). Any user may submit or read any message in these public areas. The term comes from physical pieces of board on which people can pin messages written on paper for general consumption - a "physical bulletin board". Ward Christensen, the programmer and operator of the first BBS (on-line 1978-02-16) called it a CBBS for "computer bulletin board system". Since the rise of the World-Wide Web, the term has become antiquated, though the concept is more popular than ever, with many web sites featuring discussion areas where users can post messages for public consumption. Apart from public message areas, some BBSes provided archives of files, personal electronic mail and other services of interest to the system operator (sysop). Thousands of BBSes around the world were run from amateurs' homes on MS-DOS boxes with a single modem line each. Although BBSes were traditionally the domain of hobbyists, many connected directly to the Internet (accessed via telnet), others were operated by government, educational, and research institutions. Fans of Usenet or the big commercial time-sharing bboards such as CompuServe, CIX and GEnie tended to consider local BBSes the low-rent district of the hacker culture, but they helped connect hackers and users in the personal-micro and let them exchange code. Use of this term for a Usenet newsgroup generally marks one either as a newbie fresh in from the BBS world or as a real old-timer predating Usenet. (2005-09-20)

Hermes Bulletin Board Software (BBS) by Will Price was first released in 1988 as one of the first bulletin board system applications available for the Macintosh computer.