Phishing is the name given to the practice of sending emails at random, which claim to come from a reputable company such as your bank. The emails attempt to trick people into disclosing sensitive information at a bogus website ‘phishing site’ operated by fraudsters. These emails usually claim that it is necessary to "update" or "verify" your customer account information and they urge you to click on a link in the email which takes you to a phishing site.
Sometimes the email won’t contain a link; instead the recipient is asked to provide information on a form attached to the email. Any information entered on the phishing site or form will be used by the criminals for their own fraudulent purposes.