What is Bulletin Board System?

Legal Definition
A bulletin board system, or BBS, 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 email, public message boards, and sometimes via direct chatting. Many BBSes also offer on-line games, in which users can compete with each other, and BBSes with multiple phone lines often provide chat rooms, allowing users to interact with each other. Bulletin board systems were in many ways a precursor to the modern form of the World Wide Web, social networks and other aspects of the Internet. Low-cost, high-performance modems drove the use of online services and BBSes through the early 1990s. Infoworld estimated there were 60,000 BBSes serving 17 million users in the United States alone in 1994, a collective market much larger than major online services like CompuServe.

The introduction of inexpensive dial-up internet service and the Mosaic web browser offered ease-of use and global access that BBS and online systems did not provide, and led to a rapid crash in the market starting in 1994. Over the next year, many of the leading BBS software providers went bankrupt and tens of thousands of BBSes disappeared. Today, BBSing survives largely as a nostalgic hobby in most parts of the world, but it is still an extremely popular form of communication for Taiwanese youth (see PTT Bulletin Board System) and in China. Most BBSes are now accessible over Telnet and typically offer free email accounts, FTP services, IRC and all of the protocols commonly used on the Internet. Some offer access through packet switched networks, or packet radio connections.
-- Wikipedia
Legal Definition
A computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging messages with other users, either through electronic mail or in public message boards.