Sysop (, is short for "System operator". It is a commonly used term for the administrator of a bulletin board system (BBS) or special-interest area of an online service or, historically, the operators of any computer system, especially a mainframe computer.
Usage of the term peaked in the late 1980s, being mostly used strictly to refer to BBS operators; someone doing equivalent functions on the Internet is primarily referred to as a "sysadmin", short for "system administrator", or simply "admin". However, the term has occasionally been used on the Internet, notably on MSN, CompuServe and EbaumsWorld forums.
Co-sysops were users who were granted certain admin privileges on a BBS. Generally, they would help validate users and monitor discussion forums. Some served as file clerks, describing and inserting newly arrived shareware, Freeware, and other files into appropriate download directories.
Sysops on Wikis
On Wikis sysops are usually called "admins" and have the function of blocking users who edit the wiki unconstructively. They can also unblock blocked users. Other powers and functions include protecting and unprotecting pages, editing protected pages, deleting pages and restoring deleted pages. Different Wikis vary in how much protection there is against arbitrary use of sysops power, but usually they must give a reason for a user block and decide the duration.