Phishing is a relatively new jargon in PC security area. The easiest example will be the e-mail you get in the name of Citibank and other financial institutions asking you to divulge your bank credit card numbers and similar secret numbers.
In phishing an attacker uses ‘spoofed’ e-mails and fraudulent websites designed to fool recipients into divulging personal financial data such as credit card numbers, account usernames and passwords, social security numbers, etc. By hijacking the trusted brands of well-known banks, online retailers and credit card companies, phishers are able to convince up to 5% of recipients to respond to them.

A typical e-mail that arrives as Phishing Scam:

Remedy & Response Page..
Always take all responses together to tackle any one threat. More on this..

Any Percentage is a gain:
Even if only a one percentage of people go and submit their most secretive bank codes and PINs to someone with ulterior motives, that is a gain and worth the effort.