The systematic pursuit of viruses. Techniques of virus detection may be either specific, checking for a set of known viruses, or generic, exploiting characteristics common to all viruses and aimed at detecting both known and previously unknown viruses. Techniques may be further classified into dynamic procedures, in which a permanently resident program is constantly checking the running system for viruses, or static procedures, which are invoked at regular intervals, typically daily, to detect viruses introduced since their last activation. See immunization, inoculation, signature scanning.