Computer Virus is a program / application that can replicate itself and spread by inserting itself in other programs and data. usually the user does not know if the computer in his possession terjangkit virus until one of the data is lost or the existing programs on the computer can not run. Computer viruses are generally created for bad purposes, many negative effects are caused by computer viruses such as reproduce itself so that memory becomes small, this makes the computer often hang or freeze, then change the extension on the files and programs that make the program / file it can not be used, and can also steal personal data someone without the person's knowledge. besides that virus can also damage hardware on computer.