Spam is junk email. It's annoying at best and a security risk at worst. Some spam is harmless, though irritating. However, some spam is sent by cybercriminals who are attempting to capture your personal data through innocent looking marketing emails.
Spammers send massive amounts of junk email in hopes that at least some of the recipients will click on the links or attachments. When someone clicks on a spam email, they're sent to phishing or malware websites, where they're tricked into providing personal information, activating a virus or downloading malicious software.
Spammers collect email addresses from chatrooms, websites, customer lists, newsgroups and email viruses that harvest users' address books. These addresses are then sold to other spammers.
Fortunately, there are some ways to defend yourself against spam: