Anti-Virus
Software is used to prevent, detect, and remove malware, including computer viruses, worms, and trojans

Anti-Spam
To prevent e-mail spam, both end users and administrators of e-mail systems use various anti-spam techniques

Anti-Spyware
Is a form of computer malware that deceives or misleads users into paying for the fake or simulated removal of malware

Firewall
A firewall is a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications