: Developers often use "packers" to obscure the code or "polymorphic" techniques to change its appearance, making it harder for antivirus software to detect.

If a file like virus.exe is active on your system, you might notice:

: The system becomes slow or crashes frequently.

: Viruses typically attach themselves to other legitimate files. When the infected file is opened, the virus runs and spreads to more files.

: Antivirus software may be turned off or unable to update. How to Stay Safe Download Anti Malware Testfile - EICAR