Kitten

Kittens open their eyes about seven to ten days after birth. At first, the retina is poorly developed and vision is poor. Kittens are not able to see as well as adult cats until about ten weeks after birth.
Kittens develop very quickly from about two weeks of age until their seventh week. Their coordination and strength improve, they play-fight with their litter-mates, and begin to explore the world outside the nest or den. They learn to wash themselves and others as well as play hunting and stalking games, showing their inborn ability as predators. These innate skills are developed by the kittens' mother or other adult cats bringing live prey to the nest. Later, the adult cats also demonstrate hunting techniques for the kittens to emulate.
As they reach three to four weeks old, the kittens are gradually weaned and begin to eat solid food, with weaning usually complete by six to eight weeks. Kittens live primarily on solid food after weaning, but usually continue to suckle from time to time until separated from their mothers. Some mother cats will scatter their kittens as early as three months of age, while others continue to look after them until they approach sexual maturity.
The sex of kittens is usually easy to determine at birth. By six to eight weeks they are harder to sex because of the growth of fur in the genital region. The male's urethral opening is round, whereas the female's is a slit. Another marked difference is the distance between anus and urethral opening, which is greater in males than in females.