The phone cramming scammer sends a strange, sometimes nonsensical, text through an undisclosed number. A second text then arrives with instruction that if you would like for these type texts to stop, all you have to do is reply “STOP.” But what you are really doing by replying is authorizing bogus charges on your phone bill. If you receive a strange text from an undisclosed number, or someone you don't know, and then ask you to reply—don't.

There are a million ways to steal someone's identity. Usually, someone will call or e-mail you saying there is a huge mix-up that requires you to immediately give out some sort of sensitive, personal information. Many times, these scammers claim to be calling from your bank. A new variation of this scam has become so prevalent that many hotels are posting warnings in their lobby.

Here's how it works: You get a call in your hotel room in the middle of the night. It's the front desk clerk, very apologetic, saying their computer has crashed and they need to get your credit card number again. Scammers are counting on you being too sleepy to catch on that the call isn't from the hotel at all, but from someone outside who knows the direct-dial numbers for the guest rooms. By the time morning rolls around and you are clear-headed, your credit card has been on a major shopping spree.

With so much information about us online, a scammer can sound like they know you. The most recent version of one scam appeals to our natural curiosity by appearing to be a message from a friend. When you click on the link, you are prompted to “upgrade your Flash player,” but the file you end up downloading contains a worm that logs into your social media account, sends similar messages to your friends, and searches for your personal data.

Sales scams are as old as humanity, but the Internet has introduced a whole new way to steal from others. Penny auctions are very popular because it seems like you can get something useful—cameras, computers, etc.—for well below retail. But you pay a small fee for each bid (usually 50 cents to $1) and if you aren't the winner, you lose that bid money. Winners often are not even the top bidder, just the last bidder when time runs out. Although not all penny auction sites are scams, some are being investigated as online gambling.

Hundreds of thousands, perhaps millions, of people have gotten e-mails that very much look like an official notice from a legitimate business, such as the Better Business Bureau. The subject line says something like “Complaint Against Your Business,” and the instructions tell you to either click on a link or open an attachment to get the details. If you do, typically, a malicious virus is launched on your computer that can steal banking information, passwords and other critical pieces of information needed for cyber-theft.