Creating a unified list of computer viruses is challenging due to inconsistent naming conventions. To combat computer viruses and other malicious software, many security advisory organizations and anti-virus software developers compile and publish virus lists. When a new virus appears, the rush begins to identify and understand it as well as develop appropriate counter-measures to stop its propagation. Along the way, a name is attached to the virus. Since anti-virus software compete partly based on how quickly they react to the new threat, they usually study and name the viruses independently. By the time the virus is identified, many names have been used to denote the same virus.

Ambiguity in virus naming arises when a newly identified virus is later found to be a variant of an existing one, often resulting in renaming. For example, the second variation of the Sobig worm was initially called "Palyh" but later renamed "Sobig.b". Again, depending on how quickly this happens, the old name may persist.