A new travel website offers travelers the option of putting a hold on airfare for up to 21 days without actually purchasing the ticket, according to Frommers.

The site, OptionsAway, shows the costs of each flight, with the prices, and next to that is the option to put that airfare on hold for three, seven, 14 or 21 days without purchasing it.

Robert Brown, the founder and CEO of OptionsAway.com, developed the algorithms.

"There are algorithms that are used to calculate the price of an option in the financial markets and we've used those, along with a very good understanding of airline revenue management, to calculate the probability of the movement of prices," Brown said. "This allows us to give the consumer an option on the ticket at a price that is reasonable to him and allows us to cover the risk of actually holding those flights."

The cost of holding a ticket is between $10 and $14 for a hold of seven days, a popular choice, and as little as $5 to hold a one-way ticket for three days, according to Brown.

If the site guesses correctly, when the consumer buys the ticket at the end of their option, they will pay no more than they would have on the day the hold was placed. If the site guesses wrong, either the traveler will pay less than expected because the cost of the ticket has gone down, or OptionsAway will pay the difference in cost if the price of the ticket has gone up.

If the company sees that a flight is about to sell out before an option is over, they will buy the ticket for the customer so they will still have a place on the plane if they decide to purchase the ticket, according to Jill Salzman, the PR representative for OptionsAway.