Differences between Virus, Worms and Trojan Horse

Virus

• a code fragment that copies itself into a larger program, and modifying that program
• may infect memory, floppy disk, a tape, or any other type of storage.
• virus are spread by the human action
• it need host to run

Worms

• an independent program so does not need human action to spread
• it produces by copying itself from one computer to another usually over a network
• doesn't modify program but it duplicate itself and effect the memory and the system of the computer

Trojan Horse

• a code fragment that hides inside a program and performs a disguised function
• it appear as a legitimate software also perform that function
• however it actually the program perfoms some other unauthorized operation