There are a couple of travel hacks people usually do to earn these frequent flyer miles and they are now enjoying the fruits of their labor which traveling for free!

The second most known way of racking up miles is to use credit cards. However, Nomadic Matt said that a key to travel hacking is signing up to multiple credit cards. According to him, you have to plan everything before your trip, "If I'm low on American Express points, I'll look for a new American Express card. If I want to go to Iceland, I'll sign up for an Alaska Airlines card because I can use those miles to book a rewards ticket to Iceland thanks to their partnership with Icelandair. Moreover, I always look for what card offers the highest bonuses, even if I don't need those points right away," the travel blogger said.

You just have to be mindful of your expense when using multiple cards at a time and be responsible in making payments on time. Once you get a hang of it, you will earn as much as 275,000 points a year.

TheStreet reports, "There is a huge, sprawling market of promotional offers these days because so many companies know people are salivating for these miles," says RewardExpert's Rosemary Clancy. "These miles and points have become such a hot commodity and are so commercialized, that it's become a marketing commodity for a lot of companies."

Many people have already figured out the system are now enjoying benefits from it. The Points Guy, who is a travel advisor, used to be Wall Street guy that became famous for hacking the system to earn miles and travel for free, published on TheStreet.

In addition, "It's important to always do the math. There's a reason some providers are able to offer these mileage incentives -- it's quite possible it will end up costing you more," Zach Honig, editor-in-chief for The Points Guy said.