Social media scams are nothing new, but right now there are three specific Facebook scams that are spreading.

For cyber criminals, what's the easiest way to reach the most people with one scam? Facebook. With more than a billion users, Facebook has become an easy way for scammers to rip off as many people as possible at once -- and in a variety of different ways.

Here's how to spot some big scams that are making the rounds and how to protect yourself.

3 Facebook scams to watch out for:

1. "Secret Sister"gift scam

Many Facebook and Instagram users have seen posts inviting them to spend just $10 -- with the promise that they'll receive up to 36 gifts in return. But officials say this "exchange" is actually just a pyramid scheme, meaning most people who participate aren't going to get what they expect when they sign up.

“We’re just seeing this on Facebook this time instead of the old way of using letters,” University of South Florida mass communications instructor Kelli Burns told WFLA, adding, “Facebook allows it to spread a lot faster.” 

The "secret sister gift exchange" is essentially just a classic pyramid scheme. You send a gift, send the instructions to more people, and the exchange continues on and on. So the promise is that for your first $10 gift you give, and passing on the instructions, you'll end up with 36 gifts two weeks later. The problem is, the exchange requires a lot of people to keep it going, and your odds of even getting one gift back are slim. According to one report, by the time you get to the 11th level of the exchange, it would require the entire population of the U.S. to participate to make it work.

 It's also illegal. 

There are also some concerns around the legality of these types of "exchanges." According to a report from Snopes, "In short, the problem wasn't whether any one person expected  to receive presents back -- it was the inherently unfulfillable promise that a $10 buy in would result in hundreds of dollars worth of returns for others. Whether or not a user participated "honestly" they had no hand in ensuring those who bought in under them would receive any return on their initial investment, and the risk in question problematic precisely because it was undertaken on behalf of other folks."

The U.S. Postal Inspection Service issued a statement saying it's against the law to "request money or other items of value and promise a substantial return to the participants."

The group explained why these types of gift exchanges aren't just "mathematically impossible" but also illegal: "There's at least one problem with chain letters. They're illegal if they request money or other items of value and promise a substantial return to the participants. Chain letters are a form of gambling, and sending them through the mail (or delivering them in person or by computer, but mailing money to participate) violates Title 18, United States Code, Section 1302, the Postal Lottery Statute. (Chain letters that ask for items of minor value, like picture postcards or recipes, may be mailed, since such items are not things of value within the meaning of the law.)"

 How to avoid this scam

• You've probably heard some version of the phrase, "if it seems too good to be true, it probably is." Well, that same rule of thumb applies to Facebook and every other social media site, email chain etc. Any promise of a huge return on a small investment is probably a scam!
• One warning sign that a post or offer on Facebook is a scam is if has one of those all-caps titles you can't miss -- claiming you're eligible for some "GREAT" offer, deal, discount, opportunity etc. -- and then it explains how you can "claim" the offer by sharing, signing up or even paying a fee. Don't fall for it.

2. Facebook lottery scam

Lottery scams come in all different shapes and sizes. On Facebook, the way it typically works is you get a message from someone saying you've won a huge lottery on Facebook -- but in order to claim your prize, you have to wire a payment to cover "insurance" or other fees. 

If you wire the money, it's gone. Plus, the scammers will likely continue to harass you for more "fee" payments, claiming you'll get more money in the end, but you'll just wind up wasting more money.

Even if you receive a message from a friend, never send any type of payment or wire transfer without confirming whatever it is you're paying for over the phone or in person. In some cases, criminals have hacked people's Facebook accounts and sent messages as those people -- in order to fool their friends into handing over money. 

How to avoid this scam:

• Never send money to someone for a lottery "prize" or any other offer that requires you to pay in order to get a bigger prize or money back. It's a scam.
• If you get a message from a friend on Facebook about winning something, or anything else involving sensitive information, call the friend directly or email them through a different platform in order to confirm what was sent in the message. This could also alert your friend if their account has been compromised.
• Never wire money to someone you don't know or can't confirm if the transaction is legitimate.
• These types of scams prey on seniors in particular, so it's important to carefully monitor older family members' money if you think it's necessary or that they could become a victim of a scam like this. Here are 7 senior scams to watch out for and Clark's tips to avoid them.

3. Airline ticket scam

Even if an offer that seems too good to be true comes from a legitimate source on Facebook -- or appears to -- it's still probably too good to be true.

This one has been around for a while and Southwest even posted about it on the company's Facebook page back in 2011.

The way it works is you see a post claiming that some big airline is giving away free flights for a year or some other big offer that sounds INCREDIBLE! All you have to do is share the photo, like the page and post a comment to win.

While figuring out that you fell for a scam and didn't actually win free airfare for a year is a bummer, the bigger problem is when Facebook users see fake offers like this and end up clicking on a link posted by a criminal -- which could expose everything in your computer or mobile device to the scammer on the other end.

How to avoid this scam

• Don't believe offers that are too good to be true from any airline or big company on Facebook. If you think it may be real, go to the company's website directly -- not through Facebook. 
• If you want to make sure a company page on Facebook is real, hover your mouse over the blue check mark on the profile page. If the page is legit, you'll see a pop-up that says "Verified Page." If you don't see that, then someone has created a background image to make it look like the page is verified.
• Another way to check if a company is legit is to go directly to the website and see if there is a phone number to call and/or a street address listed that you can verify.
• Always be cautious before clicking on a contest or other offer link via Facebook. If you can get to it by going to the company's website directly, do it that way. It's much safer.

Bonus tip: How to avoid email, text and phone scams

Scammers are everywhere, so it's crucial to always be cautious when: clicking on an email from an address you don't know or recognize, responding to a text from a number you don't recognize, and calling back a phone number you don't know or recognize.

Here's how to avoid these scams:

• If you receive an email claiming to be from your bank or other company that has your personal information, don't click on any of the links. It could be a scam. Instead, log in to your account separately to check for any new notices. You can also call the company about the information sent via email. 
• Responding to a text from a number you don't recognize could also make any information stored in your phone vulnerable to hackers. Do some research to find out who and where the text came from. 
• If you get a missed call on your cell phone from a number you don't recognize, don't call it back. Here's what you need to know about this phone scam.