What is a computer virus?

Computer Virus

A computer virus (often referred to as a virus) is a sub-category of malware. A virus is a malicious program (or part of computer code) that infects computers and then tries to reproduce and spread over a network. 

A virus is often hidden in a file and activated when users open the infected file. Once activated, a virus can seriously damage software and files on a computer. Sometimes people cannot access their computer after being infected with a virus.

How does a computer virus attack?

Once a virus has successfully linked to a document, program or file, nothing happens at first. You can have an infected file on your computer for a long period of time without anything happening. The virus code only becomes active when the corresponding file is opened or activated. 

A virus must therefore be activated by the user before an actual infection takes place (rather than a computer worm). However, once the virus becomes active, it can infect other computers on the same network. Many computer viruses can do all kinds of bad things on a computer, including:

  • Theft of passwords or files.
  • Registering keystrokes (reading your input).
  • Complete takeover of a computer.
  • Damaging files.
  • Harassment of your e-mail contacts with spam e-mails (often to spread the virus in this way).

Protect your computer, smartphone and tablet with antivirus software

Prevention is better than cure. Make sure that the latest virus protection package is always installed on your computer, tablet and smartphone. In the following sections you will find out which virus protection program is suitable for your device.

Virus scanner for Windows

Some good antivirus scanners for Windows, most of which offer a free version:

Virus scanner for Mac

The following antivirus programs are good and reliable for Mac computers:

Virus scanner for Android

Most of these virus scanners for Android (smartphone and tablet) are free:

Virus scanner for iOS

Most of these virus scanners for iPad and iPhone are free: