We'll give you the short, easy answer. Hopper collects massive amounts of data, amounting to more than one billion individual, real-time flight prices each day. Our expert data-science team then develops algorithms that analyze these pricing trends. Those algorithms predicts what flight prices will do, based on what they've done in the past, and power the notifications we send to Hopper users about whether to buy or wait.
If you'd like to have a look at our research blog, check it out here!