A sysop (/ˈsɪs.ɒp/, SIS-op; an abbreviation of system operator, and sometimes further abbreviated to just op) is an administrator of a multi-user computer system, such as a bulletin board system (BBS) or an online service virtual community. The phrase may also be used to refer to administrators of other Internet-based network services. Sysops typically do not earn money, but donate their activity to the community.
Co-sysops are users who may be granted certain admin privileges on a BBS. Generally, they help validate users and monitor discussion forums. Some co-sysops serve as file clerks, reviewing, describing, and publishing newly uploaded files into appropriate download directories.