There are three types of computer infestations. One being a virus, another is a worm, and last is a Trojan horse. Each of these infestations can cause great damage to a computer and/or a network, and they also attack in different ways. Anti-virus software is available to detect and remove these infestations from a computer or network, but sometimes the infestations are programmed to be undetected. Make sure to keep your software updated often or some or all of the following details could happen to you.
A virus is a program that replicates itself so as to infect more computers, either through network connections or through floppy disks passed among users. A virus may corrupt files or systems; it may simply annoy users by flashing messages or pictures on the screen, or cause the keyboard to beep. In fact, some viruses cause no harm and can remain unnoticed on a system forever. Viruses are divided into three categories: boot sector viruses, macro-viruses, and file-infected viruses. Boot sector viruses are the most common and reside on the boot sector of a floppy disk. The only way to infect a computer with a boot sector virus is to attempt to start a computer from an infected floppy disk. A macro-virus is a newer type of viruses that can take the form of a word-processing or spreadsheet program macro, which may be executed as the user works with a word-processing or spreadsheet program. These viruses were the first to infect data files rather than executable files. File-infected viruses attach themselves to executable files. When the file is run, the virus will attach itself to memory. Later, the virus will attach itself to other executable files. Since these viruses stay in memory while you continue to work on your computer, they can have devastating consequences, including infecting numerous programs. A few examples of viruses are "Stoned," "ShareFun," and "LoveBug.".
A Trojan horse is a third type of computer infestation that, like a worm, does not need a host program to work.
