Where They Infect

Viruses are programmed to infect different types of environments.  File, boot, macro, and network viruses all infect different parts of the computer.  Each one has a unique infection phase and spread differently.  Most viruses are programmed to act on only one type of virus.

There are also some viruses that may be able to infect multiple environments.  Any virus that can infect multiple types of files and disks is considered multipartite viruses.  Many of the multipartite viruses infect both a program file and a boot record.