An emotional support animal (ESA) is an animal that provides relief to individuals with "psychiatric disability through companionship." Emotional support animals are not required to be trained. Any animal that provides support, comfort, or aid, to an individual through companionship, unconditional positive regard, and affection may be regarded as an emotional support animal.

Service animals are working animals that have been trained to perform tasks that assist disabled people. Service animals may also be referred to as assistance animals or helper animals depending on the country and the animal's function. Dogs are the most common service animals, having assisted people since at least 1927.