What are Viruses, Worms and Trojan horses?
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.
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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.
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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.
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