A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and login to the system using a terminal program. Originally BBSes were accessed only over a phone line using a modem, but by the early 1990s some BBSes allowed access via a  or packet radio connection.
Once a user logged in, they could perform functions such as downloading or uploading software and data, reading news, and exchanging messages with other users. Many BBSes also offered on-line games, in which users could compete with each other, and BBSes with multiple phone lines often offered IRC-like chat rooms, allowing users to meet each other.
In recent years, the term BBS is sometimes incorrectly used to refer to any online forum or message board.
During their heyday from the late 1970s to the mid 1990s, most BBSes were run as a hobby free of charge by the system operator (or "sysop"), while other BBSes charged their users a subscription fee for access, or were operated by a business as a means of supporting their customers. Bulletin Board Systems were in many ways a precursor to the modern form of the World Wide Web and other aspects of the Internet.
Early BBSes were often a local phenomenon, as one had to dial into a BBS with a phone line and would have to pay additional long distance charges for a BBS out of the local area. Thus, many users of a given BBS usually lived in the same area, and activities such as BBS Meets or Get Togethers, where everyone from the board would gather and meet face to face, were common.
As the use of the Internet became more widespread in the mid to late 1990s, BBSes rapidly faded in popularity. Today, Internet forums occupy much of the same social and technological space as BBSes did in their heyday.
The first public Bulletin Board System was developed by Ward Christensen. According to an early interview, while he was snowed in during the Great Blizzard of 1978 in Chicago, Christensen began preliminary work on the Computerized Bulletin Board System, or CBBS. CBBS went online on February 16, 1978 in Chicago, Illinois.
With the original 110 and 300 baud modems of the late 1970s, BBSes were particularly slow, but speed improved with the introduction of 1200 bit/s modems in the early 1980s, and this led to a substantial increase in popularity.
Most of the information was presented using ordinary text or ANSI art, though some offered graphics, particularly after the rise in popularity of the GIF image format. Such use of graphics taxed available channel capacity, which in turn propelled demand for faster modems. Towards the early 1990s, the BBS industry became so popular that it spawned two monthly magazines, Boardwatch and BBS Magazine, which devoted extensive coverage of the software and technology innovations and people behind them, and listings to US and worldwide BBSes. In addition, a major monthly magazine, Computer Shopper, carried a list of BBSes along with a brief abstract of each of their offerings.
According to the FidoNet Nodelist, BBSes reached their peak usage around 1996, which was the same period that the World Wide Web suddenly became mainstream. BBSes rapidly declined in popularity thereafter, and were replaced by systems using the Internet for connectivity.
The largest BBS network was FidoNet, which is still active today, though much smaller than it was in the 1990s. Many other BBS networks followed the example of Fidonet, using the same standards and the same software. They were called Fidonet Technology Networks (FTNs). They were usually smaller and targeted at selected audiences. Some networks used QWK doors and other non Fido software and standards.
Unlike modern websites that are typically hosted by third-party companies in commercial server installations, BBS computers (especially for smaller boards) were typically operated from the SysOp's home, often in a bedroom or closet. As such, access could be unreliable, and in many cases only one user could be on the system at a time. Only larger BBSes with multiple phone lines and either multitasking software or a LAN connecting multiple computers, could have multiple simultaneous users.
A few years later in 1981, IBM introduced the first PC-DOS (MS-DOS) based personal computer, and due to the overwhelming popularity of these PCs and their clones, MS-DOS soon became the operating system that the majority of BBS programs were run under. Fido BBS was the first notable MS-DOS BBS program, created by Tom Jennings, who later founded FidoNet. There were several successful commercial BBS programs developed for MS-DOS, such as PCBoard BBS, RemoteAccess BBS, and Wildcat! BBS. Some popular freeware BBS programs for MS-DOS included Telegard BBS and Renegade BBS, which both had early origins from leaked WWIV BBS source code. There were several dozen other BBS programs developed over the MS-DOS era, and many were released under the shareware concept, while some were released as freeware.
For SysOps using the Commodore 64, (introduced in 1982) a popular commercial BBS program was Blue Board. Like other Commodore 64 BBSes, it supported PETSCII (Commodore colorized ASCII). PETSCII was also supported by the nationwide online service Quantum Link, later known as AOL.
Most BBSes remained text-based, rather than using a Graphical User Interface (GUI) design. A BBS GUI called Remote Imaging Protocol (RIP) was promoted by Telegrafix in the early to mid 1990s but it never became widespread. There were several GUI-based BBS's on the Apple Macintosh platform, including TeleFinder and FirstClass, but these remained widely used only in the Mac market.
The most popular form of online graphics was ANSI art which allowed replacing letters with IBM Extended ASCII blocks and symbols, allowed changing colors on demand, and could even include sound. During the late 1980s and early 1990s, most BBSes used ANSI to make elaborate welcome screens, and colorized menus and ANSI support was a sought-after feature in client programs.
In the early 1990s a small number of BBSes were running on the Commodore Amiga models 500, 1200, 2000, and 3000, (using external hard drives), and the Amiga 4000 (which had a built-in hard drive). Popular BBS software for the Amiga were ABBS, Amiexpress, Infinity and Tempest.
MS-DOS continued to be the most popular Operating System for BBS use up until the mid-1990s, and in the early years most multi-node BBSes were running under a DOS based multitasker such as DesqView. By 1995 many of the MS-DOS based BBSes had switched over to OS/2, NT 4.0, Windows 95, or even Linux using DOSEmu.
By the late 1990s the most of the remaining BBSes evolved to include Internet hosting capabilities, either by using modern BBS software such as Synchronet, EleBBS or Wildcat! BBS using the  protocol rather than dialup, or by using legacy MS-DOS based BBS software with a FOSSIL to Telnet redirector such as NetFoss.
Pay BBSes such as The WELL and Echo NYC (now Internet forums rather than dial-up), ExecPC, and MindVox (which folded in 1996) were admired for their tightly-knit communities and quality discussion forums. However many "free" BBSes maintained close knit communities and some even had annual or bi-annual events where users would travel great distances to meet face-to-face with their on-line friends.
Some BBSes, called "elite boards" or "Warez boards", were exclusively used for distributing illegally copied software. These BBSes often had multiple modems and phone lines, allowing several users to upload and download files at once. Most elite BBSes used some form of new user verification, where new users would have to apply for membership and attempt to prove that they weren't a law enforcement officer or a lamer. The largest elite boards accepted users by invitation only.
Another common type of board was the "support BBS" run by a manufacturer of computer products or software. These boards were dedicated to supporting users of the company's products with question & answer forums, news and updates, and downloads. Most of them were not a free call. Today, these services have moved to the web.
BBSing survives as a niche hobby for those who enjoy running BBSes and those users who remember BBSing as an enjoyable pastime. Most BBSes are now accessible over  and typically offer free email accounts, ftp services, IRC chat and all of the protocols commonly used on the Internet.
Some BBSes are Web-enabled and have a Web-based user interface, allowing people who have never used a BBS before to use one easily via their favorite web browser. For those more nostalgic for the true BBS experience, one can use NetSerial (Windows) or DOSBox (Windows/*nix) to redirect DOS COM port software to telnet, allowing them to connect to Telnet BBSes using 1980s and 1990s era modem terminal emulation software, like Telix, Terminate, Qmodem and Procomm Plus. Modern 32-bit terminal emulators such as mTelnet and SyncTerm include native telnet support.
The website textfiles.com serves as a collection point of historical data involving the history of the BBS. The owner of this site produced BBS: The Documentary, a program on DVD that features interviews with well-known people (mostly from the United States) from the "hey-day BBS" era.
Many commercial BBS software companies that continue to support their old BBS software products switched to the shareware model or made it entirely free. Some companies were able to make the move to the Internet and provide commercial products with BBS capabilities.
The BBS software usually provides: