Phishing is, according to Wikipedia, "the attempt to acquire sensitive information such as usernames, passwords, and credit card details (and sometimes, indirectly, money), often for malicious reasons, by masquerading as a trustworthy entity in an electronic communication."

In its most common form, phishing is the sending of an email containing a link that appears to be from a trusted source, e.g., your credit union, but really isn't.

In the early days of phishing, such attacks were largely directed at consumers. The cyber-criminal would send out a massive number of emails claiming to be from, for example, Bank of America. The email would alert the consumer to some sort of security breach that required the consumer's attention, instructing said consumer to click the link to log on to home banking and resolve the matter.