Glossary What is a virus, trojan, spyware, malware or other
badware The technical terminology used in virus alerts and
descriptions can be confusing. The glossary below contains
definitions for some of the most common terms with the top ones
linked just below. A legitimate, non-replicating program
designed to display ads to the end-user, often based on
monitoring of browsing habits. Often adware contains spyware in
order for the program to know which advertisements to display
based on the current user’s preference. Adware displays ads
often in exchange for the right to use a program free of charge
(a variation on the shareware concept). A program that opens
secret access to systems, and is often used to bypass system
security. A Backdoor program does not infect other host files,
but nearly all Backdoor programs make low-level operating system
modifications (i.e. it makes changes to the registry). Backdoors
usually hitch a ride in on trojans. Once they are in place and
they have executed, they hide themselves