Automatic transmissions are a world apart from most manual transmissions because of the complexity of their operation. However, in function, they are the same. Automatic transmissions help optimize engine torque and also provide a reverse gear in the same way a manual transmission does. The difference is how an automatic transmission does this. Automatic transmissions have a whole host of different components and controls to accomplish the task.
Having a general idea of these parts and how they operate is a good start when dealing with automatic transmission problems. Given the complexity of the automatic transmission, I would advise you take the work to a professional, or you replace it as a unit if you run into problems with one. Servicing automatic transmissions requires a lot of special tools as well as specialized knowledge and experience. If you are missing any one of those, you're going to have a hard time of it, and your chances of success are very slim. This section of the article will walk you through the basics if you run into an automatic transmission problem. For specifics, consult the service manual for the vehicle you're working on. To see what's inside an automatic transmission, check out these videos on the basic parts.