A common type of malicious software (malware) that, when executed, replicates itself by inserting copies (possibly modified) into other computer programs, data files or the hard drive'
s boot sector; if this replication succeeds, the affected areas by it are often said to be "infected". Viruses often perform some types of harmful activities on infected hosts, such as stealing hard drive'
s space or the CPU
time, accessing private/sensitive information, displaying political or humorous messages on the user'
s screen, spamming their contacts, or logging user'
s keystrokes. However, not all viruses carry destructive payloads or attempts to hide.
A good majority of them
target computers running
Windows.
Computer viruses currently cause billions of dollars worth of economic damage. In response, when it was during the 90'
s decade, it led to the emergence of the billion-dollar antivirus industry, selling anti-malware protection to users.
