Phishing

"Phishing" refers to an e-mail scam that attempts to trick a person out of confidential information like Social Security and credit card numbers.

E-mail phishing involves a fake e-mail that appears to come from a legitimate source (eBay, for example) that attempts to have the user follow a link in the e-mail to a webpage where he needs to enter his account information. The link, while appearing to go to a legitimate eBay site, will instead redirect the user to a website run by the phisher. Most of the time, the site will look exactly like a legitimate page. However, when the user enters his information into the page, that information will be sent to the phisher, not eBay.

This Dilbert cartoon sums it up pretty accurately.