A program that can pass on the malicious code to other program by modifying them.
It attaches itself to the program usually files with .doc, .xls, and .exe.
A program that copies itself and spread through the network.
The differences between worm and virus:
- Worm operates through the network while viruses spreads through any medium.
- Worm spread copies of itself as a stand alone program while viruses spread copies of itself as a program that attaches to other program.