| A | B |
| Trojan Horse | deguised as useful |
| Hoax | a program intended to scare users into thinking they have a virus |
| Bomb | set to go off at specific time |
| Commercial software | copyrighted software |
| Shareware | Software must be paid for after trial period |
| Public domain | Free to everyone |
| Worm | Bores its way through computer system |
| Piracy | the illegal copying of software |
| Hacker | A person who gains access to computers without permission |
| Freeware | Software given away free, but author retains rights |