A pet is an animal that lives with people as a companion rather than for work or food. Dogs, cats, hamsters, fish, birds, and many other creatures can be pets. Unlike farm animals that produce milk or eggs, or working animals that herd sheep or pull carts, pets exist primarily to share our lives and homes.

People keep pets for companionship, entertainment, and the joy of caring for another living creature. A pet dog greets you enthusiastically when you come home from school. A pet cat might curl up, purring, in your lap while you read. Even watching fish swim peacefully in a tank can be calming and enjoyable.

Keeping a pet means taking responsibility for another creature's well-being. You must feed your pet regularly, make sure it has fresh water, keep it healthy, and give it attention and exercise. A neglected pet suffers, while a well-cared-for pet thrives and brings happiness to its owner.

The word pet can also work as a verb, meaning to stroke or pat an animal affectionately. When you pet a friendly dog, you're running your hand gently over its fur. Some animals love being petted, while others prefer to be left alone.

As an adjective, pet can mean “favorite” or “specially cared for.” People sometimes call their favorite thing a pet project, meaning something they care about deeply and work on with special attention, just as they would care for a beloved animal.