Cats are domesticated species of carnivorous mammals. They are in the family Felidae and commonly referred to as house cats. They are commonly kept as house pets, but they can also be farm or feral cats; Feral cats range freely and avoid human contact. Domestic cats are valued by humans for companionship and their ability to kill rodents.
Outdoor cats are active both day and night, mostly night. Domestic cats spend most of the times in the vicinity of their homes, they establish territories that vary in size. Cats conserve energy by sleeping more than most animals, especially as they grow older. Their duration of sleep usually varies between 12 and 16 hours, with 13 and 14 being the average. The average lifespan of cats has risen during the decades. In the 1980s it was about seven years, then in 1955 it rose to 9.4 years. Some cats have survived up to their 30s.