Outdoor cats are active both day and night, although they tend to be slightly more active at night. Domestic cats spend the majority of their time in the vicinity of their homes, but can range many hundreds of meters from this central point. They establish territories that vary considerably in size, in one study ranging from 7 to 28 hectares (17–69 acres). The timing of cats' activity is quite flexible and varied, which means house cats may be more active in the morning and evening, as a response to greater human activity at these times.

Cats conserve energy by sleeping more than most animals, especially as they grow older. The daily duration of sleep varies, usually between 12 and 16 hours, with 13 and 14 being the average. Some cats can sleep as much as 20 hours. The term "cat nap" for a short rest refers to the cat's tendency to fall asleep (lightly) for a brief period. While asleep, cats experience short periods of rapid eye movement sleep often accompanied by muscle twitches, which suggests they are dreaming.

The social behavior of the domestic cat ranges from widely dispersed individuals to feral cat colonies that gather around a food source, based on groups of co-operating females.

Life in proximity to humans and other domestic animals has led to a symbiotic social adaptation in cats, and cats may express great affection toward humans or other animals. Ethologically, the human keeper of a cat functions as a sort of surrogate for the cat's mother. Adult cats live their lives in a kind of extended kittenhood, a form of behavioral neoteny. Their high-pitched sounds may mimic the cries of a hungry human infant, making them particularly difficult for humans to ignore. Domestic cats' scent rubbing behavior towards humans or other cats is thought to be a feline means for social bonding.

Domestic cats use many vocalizations for communication, including purring, trilling, hissing, growling/snarling, grunting, and several different forms of meowing.

Cats are known for spending considerable amounts of time licking their coats to keep them clean. The cat's tongue has backwards-facing spines about 500 μm long, which are called papillae. These contain keratin which makes them rigid[114] so the papillae act like a hairbrush. Some cats, particularly longhaired cats, occasionally regurgitate hairballs of fur that have collected in their stomachs from grooming. These clumps of fur are usually sausage-shaped and about 2–3 cm (3⁄4–1+1⁄4 in) long. Hairballs can be prevented with remedies that ease elimination of the hair through the gut, as well as regular grooming of the coat with a comb or stiff brush.