A computer virus is a type of malicious software (malware) that is designed to replicate and spread itself from one computer to another. It does this by attaching itself to legitimate programs or documents, and when these are opened, the virus is activated and can execute its code on the infected computer.
Computer viruses can have a variety of effects on infected computers, ranging from relatively benign to very damaging. Some viruses may simply display annoying messages or cause the infected computer to slow down, while others can delete or corrupt important data, or even take control of the infected computer and use it to attack other computers.
Computer viruses are often spread through email attachments, file-sharing networks, or by downloading infected files from the internet. It is important to be cautious when opening email attachments or downloading files and to keep your antivirus software up to date to help protect against infection.