There's no shortage of websites offering last minute travel deals. The idea behind these deals is that if a hotel is going to have a room empty or a flight is going to have an empty seat, it's better for them to offer it to you at the last minute for a steep discount than it is to just let that spare capacity go to waste.
The big contradiction of last minute travel, however, is that while the places with a lot of spare capacity get cheaper, the places with very little get much more expensive. Booking Christmas flights at the last minute, for example, will never get you a good deal, simply because so many people want those flights. Instead, you will probably end up paying much more than you would have if you had booked early.
As last minute travel deals are for the least in-demand places, you can end up with places that no-one wanted for a reason. Some of the hotels on offer can't attract any customers because they're truly dire. The flights on offer are often in the middle of the night, at times when it's very difficult to even get to the airport without a car because the public transport links are closed. There are all sorts of gotchas waiting with cheap last minute travel.
But it is cheap, and, as ever, that makes up for all sorts of sins. If you're willing to be flexible about when you fly and where you go, you can still get some very good deals - you'll probably end up with the all-round budget experience, but what do you expect? To avoid the very worst holidays, though, you should at least take the time to look up a review of the hotel you're going to stay in before you commit to booking it, no matter how good the deal seems, to make sure that you're not getting yourself into anything truly terrible.