As the summer travel season approaches, were once again reminded just how expensive taking a trip can be. Airline tickets continue to surge in cost, even outpacing inflation , so reaching the buzzy places where everyone somehow seems to be vacationing might not fit into even the most seasoned travelers budget.

But before you give up on your dreams of visiting the beautiful international destinations that inundate TikTok and Instagram on a daily basis, just know that a golden opportunity could arise in the form of mistake fares.

But what exactly are mistake fares and how do they work? Below, travel experts break down what you should know.

What are mistake fares?

The term mistake fare generally refers to an airline ticket price that is significantly different from historical norms and/or what an airline intended, Nick Ewen , senior editorial director at The Points Guy, told HuffPost.

He pointed to a well-publicized mistake fare from Cathay Pacific in 2018 that allowed travelers to book round-trip tickets between Vietnam and the United States for less than $700 in business class and under $1,000 in first class.

Theres not a definitive line between what makes for a deal vs. a mistake in this context, but usually a mistake fare is orders of magnitude lower than normal, Ewen said. For example, a $1,000 round-trip flight from the U.S. to Europe in business class could be a deal if its on a Tuesday in mid-January to Poland.

If the flight is on a peak summer travel date between the U.S. and Rome, however, thats more likely to be a mistake.

Mistake fares happen when airlines incorrectly file the price of a given flight, said Zach Griff , a senior reporter at The Points Guy. One of the recent mistake fares I found was a $700 round-trip ticket in Air France first class from Algeria to New York. That ticket typically retails for over $10,000, so its pretty clear that something was wrong with how it was pricing. Just note that no airline website will market something as a mistake fare.

Why do they happen?

Mistake fares can happen for many reasons, but some of the common reasons are currency conversion errors with travel agencies that incorrectly convert the fare into the local currency or vice versa, as well as fat-finger errors from revenue management analysts who potentially miss a digit when inputting a fare or file a fare for business class at the price of economy, Griff said.

Basically, an airline employee might accidentally leave off a zero or use the wrong fare code during the ticket pricing process, thus giving travelers the opportunity to snag business-class tickets for economy prices.

The reason could be related to an automated system as well.

A pricing algorithm may be incorrectly calibrated to drop prices precipitously when demand drops, Ewen said. Or a currency conversion error may display the right number but in the wrong currency e.g., a flight that should be 5,000 U.S. dollars could show as 5,000 Hong Kong dollars, which is less than 650 U.S. dollars.

Although these situations do occur, the odds that you will stumble upon one of these magically low fares are low.

Mistake fares are like four-leaf clovers rare but not unheard of and very lucky, said Katy Nastro, a spokesperson for the flight alert service Going . They have become less common over the years due to better technology that rectifies the pricing before it becomes widely known.