What is spoofing in IT?

The most common sort of spoofing online is ‘e-mail spoofing’, i.e making an e-mail message appear to have come from one place when really it comes from another. It is generally used by spammers, who do not want their real address to appear on the e-mails they send. Since the messages they send out have web links in them, they do not care if people click `reply’ and send an e-mail to the wrong place. It also makes it a lot harder for ISP to track them down and close their accounts.