Spoofing. Any situation in which scammers masquerade as a specific person, business or agency. The term is typically used to describe the manipulation of telephone Caller ID to display a false name or number for the caller.
Spyware. A type of malware installed on computers or cellphones to track your actions and/or collect information without your knowledge. Some spyware can change computer settings for pharming redirection.
Trojan horse. Software that's hidden within apparently harmless data — or masquerades as a regular program — and when activated, can deliver such blows as corrupting data on your hard drive or sending files and account information to hackers. Unlike viruses and worms, Trojans do not self-replicate and spread to other computers.
Vishing. Short for "voice phishing," it's the use of recorded messages to telephones — usually claiming to be from a bank — with the goal of tricking you into revealing personal or account information for identity theft.
Virus. A computer program that can replicate itself and spread from computer to computer or file to file. It comes to life only when you take a specific action, such as running a particular program.
Worm. Like a virus, it can replicate itself and spread — but without any action by you.
Sid Kirchheimer is the author of Scam-Proof Your Life, published by AARP Books/Sterling.