Computer Virus

Computer Virus is a program designed to spread itself by first infecting executable files or the system areas of hard and floppy disks and then making copies of itself. Viruses usually operate without the knowledge or desire of the computer user. Closely related to computer viruses are Trojan Horses and Worms.

• Trojan Horse is a program that performs some undesired yet intended action while, or in addition to, pretending to do something else. One common class of trojans are fake login programs-collecting accounts and passwords by prompting for this information just like a normal login program does. Another is a disk defraggre that erases files rather than reorganizing them. A Trojan Horse differs from a virus in that the former does not attempt to reproduce itself.

• A Worm is just a self - propagating virus.