Alignment & Balancing
If your tires are not aligned properly, your steering can pull to the right or left, you can have uneven tread wear on the edges of your tires, and lower fuel economy. Typically, your car is put on a special lift (with all the tires on the car) and they put sensors on your wheels. The computer reads the sensors, and tells the tech how much and which direction to adjust each wheel so they are aligned properly.
You should always balance a new tire. Any time a tire is removed and put back on a wheel it should be balanced. Otherwise it will certainly vibrate or wobble. Balancing is when they spin your wheel and tires really fast on that machine, and then they add little weights on them to make them spin smoothly.