Virus

A computer virus is an unwanted program that embeds itself into other programs that are shared among computer systems and replicates itself. Viruses typically behave in a destructive, disruptive manner, impeding the operations of the programs it has infected. A virus often times infects files on a network file system or a file system accessed by other computers. In order to replicate, the virus must be able to execute code and write it to memory, which is why they attach themselves to executable files in legitimate programs. When users launch the program that has been infected, the virus’ code is also executed. A virus that has been executed remains active in background programs and continues to infect new hosts as additional programs or files are accessed by the operating system.