Hold onto your seats: we're in for a whole new round of virus attacks, so we thought it a good idea to give you a little refresher in terms you'll be hearing a lot in the next few weeks.

This list isn't complete, but it's a good start:

Attack
An attempt by an unauthorized individual or program to gain control over aspects of your PC.
Backdoor
Code inserted into a program by the original programmer in order to fix bugs or make other changes that need to be made. If the wrong person finds it, it can be used to attack your computer.
Hijacking
An attack whereby an active session is intercepted and used by someone else.
Key
A key is a Windows registry components that tells Windows what program to run when an icon is clicked, or what kind of printer you have. Every time a program gets added to or uninstalled from a PC the registry gets changed. Viruses usually add keys to your registry, making your computer do things it shouldn't do.
@mm
If you see this at the end of a virus, it means the virus is a mass mailer. A mass mailer is the term for a virus that upon infection can mail itself out to email addresses that it harvests from various areas of your hard drive -- especially your address book.
Macro virus
Code written to take advantage of 'Hotkey" programming in email clients to deliver its payload or replicate. Macros are key combinations that can be recorded and linked to a single keystroke -- so when you open the email and unknowingly hit the hotkey, your computer gets infected.
Replication
After a virus successfully infects a PC it usually wants to copy itself -- to replicate itself. It tries to infect either different parts of your system, or other systems, usually through address books or shared network files.