A computer virus (Latin virus, poison, Schleim ‘) is a self-propagating computer program, which infiltrates into other computer programs and thus reproduces itself. The classification as a virus refers here to the distribution and infection function.

Once started, it can make uncontrollable changes to the status of the hardware, the operating system or other software (damaging function). Computer viruses can interfere with computer security by the creator desired or unwanted functions and count to Malware.
The term computer virus is colloquially also used for worms, ransomware, rootkits, spyware and trojans, since there are often mixed forms and for users the difference is barely recognizable.