IntroductionComputer virus is a program or codes that are loaded onto your computer without your knowledge and work against your wishes and can copy itself. In this research I will talk about computer viruses and different types of computer viruses and how they infect the computer.Computer virusIt is an external program with the purpose of deliberately modifying the properties of the files they infect to implement some removal or modification commands or vandalism and other similar operations. In other words, computer viruses are programs written for the purpose of harming another compatible or to control and are written in a certain way many styles and are highly developed. (Fenlon, M, 2013 )Computer virus characterized as:1- A program copies and replaces itself.2- The computer virus connects to another program called an incubator.3- The computer virus cannot establish a host on its own. 4- The computer virus can move from an infected computer to another undamaged one. The computer virus is composed of four main parts:1- The replication mechanism: it is the part that allows the computer virus to copy itself.2- The protection mechanism: this part hides the computer virus from detection.3- The trigger Mechanism: allows the virus to spread before the user notices its presence.4- The payload mechanism: the part that executes the computer virus .Types of files that the virus can infect:Generally the virus infects executable files or encrypted files is a text such as the following: Files and data records (boot volume records) in floppy disks and a solid record number (0 ) in the main boot of the hard drive. (Kanish, 1997)General purpose files such as patch files and script files and......middle of paper......ConclusionComputer viruses are very dangerous for the computer and can damage it even for students who they may lose their important files and research. You should protect your computer from viruses by installing antivirus software and scanning your computer daily. Reference: Kanish, B. (1997, 1 25). virus32. Retrieved 10 10, 2013, from hicom: http://www.hicom.net/~oedipus/virus32.html Weinberger, S. (2012, 3 20). The ten most destructive computer viruses. Retrieved 10.11.2013 from Smithsonianmag: http://www.smithsonianmag.com/science-nature/Top-Ten-Most-Destructive-Computer-Viruses.htmanonymous. (2013). morevirusinfo. Retrieved 10.12.2013 from http://acms.ucsd.edu/units/resnet/morevirusinfo.html.Fenlon, MB(nd). virus. Retrieved June 10, 2013, from howstuffworks: http://www.howstuffworks.com/virus.htm