Have you ever heard the term "phishing"? Well, if not, I guarantee at some point you have received a phishing email message and maybe you didn't even realize it. Wikipedia defines phishing as "the criminally fraudulent process of attempting to acquire sensitive information such as usernames, passwords and credit card details by masquerading as a trustworthy entity in an electronic communication." Wikipedia also has a great explanation article detailing it further found here: http://en.wikipedia.org/wiki/Phishing. The flowchart below will help you determine whether or not you have received an email message that is a scam.
You can find the chart here: http://loginhelper.com/email/phishing-flow-chart/.