Supplemental security software (such as anti-virus [anti-malware]) is: Generally considered essential for all desktops and laptops. An optional addition. Already included by the manufacturer on all computers. Generally considered essential for personally-owned devices only.

With an anti-virus, we can search, detect, and delete malware like spyware, worms, Trojans, rootkits, pseudoviruses, etc.

An anti-virus can detect virus with several methods like:

Digital signature Heuristic detection Behavior detection Sandbox detection

Is necessary for personal laptops and desktops, even in companies hardware.