What is a virus?
A virus is a program that can copy itself and infect various parts of your computer, such as documents, programs, and parts of your operating system. Most viruses attach themselves to a file or part of your hard disk and then copy themselves to other places within the operating system. Some viruses contain code that inflicts extra damage by deleting files or lowering your security settings, inviting further attacks.
What is a worm?
A worm is a program that makes copies of itself and can spread outside your operating system; it can copy itself from one computer to another by using e-mail or another transport mechanism. Worms can damage computer data and security in much the same ways as viruses, but are different from viruses in that they copy themselves from system to system.
What is a Trojan horse?
A Trojan horse is a harmless-looking program designed to trick you into thinking it is something you want, but which performs harmful acts when it runs. It is typically received through downloads from the Internet. Trojan horses do not spread by themselves like viruses and worms. Most virus protection programs only detect a limited number of Trojan horses. A good way to help protect your computer from Trojan horses is to visit only Web sites you trust, and avoid downloading things unless you trust the source as well.
How do antiviruses programs help protect my computer?
Antivirus programs scan e-mail and other files on your computer for viruses, worms, and Trojan horses. If a virus, worm, or Trojan horse is found, the antivirus program either quarantines it or deletes it entirely before it damages your computer and files.
Some companies that make antivirus programs provide regular updates for viruses. Many antivirus programs have an automatic update capability. When your antivirus software is updated, new viruses are added to a list of viruses to check for, protecting your computer from new attacks. If your antivirus updates are not automatic, we recommend that you check for updates on a frequent basis because new viruses are identified every day. If the antivirus program you are using requires a subscription, we strongly recommended that you keep the subscription current to receive regular updates. If your list of viruses is out of date, your computer is vulnerable to new threats.
To find out if your computer has antivirus software
Use this procedure if you are unsure whether or not you have antivirus software installed on your computer. Many major computer manufacturers include at least a trial version of antivirus software. But just because the software is installed, doesn't mean it's running or being updated regularly.
Click Start, and then point to All Programs (or point to Programs if you are using the classic Start menu).
In the list of programs, look for the word "antivirus."
If you do not have antivirus software installed, you should purchase and install an up-to-date antivirus program to help protect your computer. For a list of popular antivirus programs
