People call it a "tire alignment" or a "wheel alignment", but it's more than that. Your car or truck is aligned when all the parts of the steering and suspension system are lined up right. That makes everything work more smoothly, with less effort.
It's worth getting a tire alignment service a couple of times a year. The cost of tire alignment is easily balanced out by the savings in fuel and wear on your tires. It makes your car or truck safer, too.