Cats purr when they are happy, even while they eat. A cat can also purr when it is hurt, hungry or nervous. So a purr does not always mean a happy cat.

Kittens may purr when they drink their mother's milk. A mother cat purrs to her kittens. This is thought to help them feel calm.

Kittens finish drinking their mother's milk by about 8 weeks old. They learn to hunt by copying their mother. Their play is hunting practice. They stalk, chase, pounce and bite.

Kittens learn to be at ease with people and other animals most easily between 2 and 7 weeks of age.

Cats can see well when there is only a little light. Their eyes glow in dim light. A mirror-like layer behind the retina bounces light back.

Cats have a strong sense of smell. A cat may open its mouth a little and pull back its upper lip after a smell. It is sending the scent to a special smelling organ.

People and cats have lived together for thousands of years. Wildcats probably came to early farming villages. Grain stores drew mice and other rodents, and the cats hunted them.

Cats traveled the world on ships. There, they helped keep rodents away.

Words to know

• purr: soft cat hum
• rodents: mice and rats
• retina: inside the eye
• stalk: sneak up on
• organ: body part