A computer virus is a type of malware that replicates itself by inserting its code into other programs or files on a computer. Like a biological virus, a computer virus spreads from host to host and can cause a range of problems, from annoying pop-ups to data theft or system crashes.

There are many different types of computer viruses, including boot sector viruses that infect the boot sector of a disk or drive, file infectors that attach themselves to executable files, macro viruses that infect document files, and email viruses that are spread through email attachments. In some cases, a virus may remain dormant until a specific trigger is met, such as a certain date or the user performing a specific action.

Viruses can be spread through a variety of methods, including infected websites, malicious email attachments, and infected software downloads. Once a virus has infected a computer, it can cause a range of problems, such as slowing down the computer, corrupting files, stealing personal information, and spreading to other computers on the same network.

Preventing virus infections requires a multi-layered approach. This includes using anti-virus software that can detect and remove viruses, keeping operating systems and software up to date with security patches, being cautious when opening email attachments or downloading files from the internet, and avoiding suspicious websites.

If you suspect that your computer has been infected with a virus, it's important to take action as soon as possible. This may include running a virus scan, disconnecting from the internet, and seeking the help of a trained professional if necessary.

In conclusion, computer viruses are a serious threat to computer security and can cause a range of harmful effects on users and their systems. Preventing infections and responding quickly to suspected infections are key steps in protecting against this threat.