A virus is a specific type of malware that spreads by attaching itself to legitimate files and programs. It is activated when the victim opens the infected application or file. Once activated, it can delete or encrypt files, disable functions, modify applications, etc. The most intriguing type is the polymorphic virus. It can modify its own code to evade detection by antivirus programs. The malware statistics show that 97% of all viruses in 2020 had polymorphic abilities.