In order to answer a question better, it is always good to include model year, mileage, and any unusual operation aspects of your vehicle.
In general, I agree with DJMurphy. But, sometimes a single part can go bad prematurely and it is o.k. to just replace that part. An outer tie rod is a good example, and if you take care you can get that part of an alignment back to spec. on your own. One of the biggest challenges is finding good replacement parts. The traditional reliable companies like MOOG are going downhill due to bean counters and outsourcing manufacturing to third world countries.
The best way to learn what these components are is through Google to SEE and read about them. Tie rods are the connectors that go between the wheel and steering gear - turn the steering wheel and the tie rods push or pull the wheels in the direction desired. The control arms are part of the suspension that connects your wheel assemblies to the "frame" of your car. All these parts have to twist and turn multiple angles and have metal and/or rubber joints (think knee and hip joints) that can wear. And, everything has to be set up near perfect so your wheels travel straight down the road at 80 miles an hours.
