What is “spoofing”?

Spoofing is, generally, the act of one person pretending to be someone else, usually in an effort to scam someone or otherwise commit either fraudulent or fairly malicious acts. The word “spoof” is often used in entertainment to mean a type of media that uses imitation to parody another program or work of entertainment. In the sense that it is used in security and fraud, however, spoofing is used because a person is using imitation to appear to be another person or service and gain sensitive information or otherwise maintain an advantage over the unwitting victim.