In exchange for a few hundred dollars, airlines give you a few cubic feet that are yours while they whisk you across the country or across the world.

Airlines also give you a special little button with which you can increase your cubic footage by a tiny bit and gain some comfort. It doesn’t cost you anything to press the button, but your additional square footage comes at the expense of the person behind you — and if he or she is working on a laptop, it might make typing hard.