A bulletin board is a surface intended for the posting of public messages, for example, to advertise things to buy or sell, announce events, or provide information. Bulletin boards are often made of a material such as cork

Cork (material)

Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber , which is endemic to southwest Europe and northwest Africa...

 to facilitate addition and removal of messages or it can be placed on the computer so people can leave and erase messages for other people to read and see.

Bulletin boards are particularly prevalent at universities. They are used by many sports groups and also advertisements by extracurricular groups and anything from local shops to official notices. Dormitory

Dormitory

A dormitory, often shortened to dorm, in the United States is a residence hall consisting of sleeping quarters or entire buildings primarily providing sleeping and residential quarters for large numbers of people, often boarding school, college or university students...

 corridors, well-trafficked hallways, lobbies, and freestanding kiosks often have cork boards attached to facilitate the posting of notices. At some universities, lampposts, bollards, trees, and walls often become impromptu posting sites in areas where official boards are sparse in number.

Internet forums are becoming a global replacement for traditional bulletins. Online bulletin boards

Bulletin board system

A Bulletin Board System, or BBS, is 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...

are sometimes referred to as message boards. The terms bulletin board, message boards and even Internet forums are interchangeable, although often one bulletin board or message board can contain a number of Internet forums or discussion groups. An online board can serve the same purpose as a physical bulletin board.

Magnet boards, or magnetic bulletin boards, are a popular substitute for cork boards because they lack the problem of board deterioration with the placement of pins over time.