Auto is a shortened form of “automobile,” which is another word for car. People use auto all the time in compound words and phrases: an auto mechanic fixes cars, auto insurance protects drivers from accidents, and the auto industry includes all the companies that design, build, and sell vehicles.

The word comes from Greek, where auto means “self.” An automobile is a vehicle that moves itself (unlike a horse-drawn carriage, which needs an animal to pull it). You'll see this same prefix in many other words: an autobiography is a book someone writes about their own life, and something that happens automatically happens by itself without someone having to make it happen.

When you see auto at the beginning of a word, it almost always signals that something is working on its own or relates to oneself. Autopilot lets a plane fly itself, and autofocus means a camera focuses itself without you having to adjust it manually.