American Alligators are found in the subtropical southeast region of the United States. They live in freshwater environments, such as ponds, marshes, wetlands, rivers, lakes, and swamps, as well as brackish environments.

Large male alligators are solitary, territorial animals. Smaller alligators can often be found in large numbers in close proximity to each other. The largest of the species (both males and females), will defend prime territory; smaller alligators have a higher tolerance of other alligators within a similar size class.

Although alligators have heavy bodies and slow metabolisms, they are capable of short bursts of speed, especially in very short lunges. Alligators' main prey are smaller animals that they can kill and eat with a single bite. Alligators may kill larger prey by grabbing it and dragging it in the water to drown. Alligators consume food that cannot be eaten in one bite by allowing it to rot or by biting and then spinning or convulsing wildly until bite-size pieces are torn off. This is referred to as the "death roll."

Most of the muscle in an alligator's jaw is intended for biting and gripping prey. The muscles that close the jaws are exceptionally powerful, however the muscles for opening their jaws are relatively weak.

Alligators are generally timid towards humans and tend to walk or swim away if one approaches. Unfortunately, this has led some people to the practice of approaching alligators and their nests in a way that may provoke the animals into attacking. Attacks on humans are few but not unknown. Alligators do not immediately regard a human as prey, but may still attack in self-defense if antagonized.

The eyes of a large alligator will glow red and those of a smaller one will glow green when a light is shined on them. This fact can be used to find alligators in the dark.