Basically, the “tool” is a website that features a personalized graph that was created based on data from Google Flights, hotel search, and things to do from Google.com. To find out when you should book your flight, the page lets you choose from an origin city to a destination. It also requires you to put in a time frame for travel. Then it shows you a graph of prices and how far in advance to book, based on data from last year of this same flight route and time frame. Currently, it only offers origin cities from Los Angeles, New York City, San Francisco, Chicago, and Washington. Get the full story at TechCrunch and Google