The term kitten most commonly refers to a pre-adolescent cat. It may also refer to a young rabbit or rat.
A litter of kittens usually consists of three to six kittens. Born after approximately 63 days of gestation, kittens emerge in an amnion which is bitten off and eaten by the mother cat. Their eyes remain closed for their first week to 10 days of life.
Between 2 and 7 weeks kittens develop very quickly. Their coordination and strength improve and they spar with their litter-mates and begin to explore the world outside the nest. They learn to wash themselves and others and to play hunting and stalking games. If they're outdoor cats their mother or other adult cats may demonstrate hunting techniques for them to emulate.
Gradually as they reach 2 months of age the kittens are weaned and begin to eat solid food. Any time after 2 months they can be adopted out to new owners.
Between 2 and 6 months the kittens grow quickly, going through a "leggy" and energetic phase. By one year, the kitten has become a cat, although some larger breeds may take a few more months to attain full adult size.
The young of cats larger than the common domestic cat are usually called cubs rather than kittens.
Kittens should be examined by a veterinarian and given their first shots, as well as being checked for parasites. Vaccination schedules vary regionally: the veterinarian will advise you on what is recommended and when to bring the kitten back for booster shots in the future.
Many veterinarians and humane organizations recommend spaying or neutering kittens in order to keep cat population in check (presuming they are not going to be bred as an adult). Females should be spayed at 5 months of age, and males should be neutered at 6 months of age. Many veterinarians advise delaying neutering until the kitten is six months old because they believe that it affects the hormone levels and can cause problems. However, studies have found no difference in development or health between kittens spayed at 12 weeks and those spayed at six months and many vets perform early spaying on healthy kittens.
While caring for a baby kitten between the ages of one day old and 1 month old is hard, one needs to take very good care of them or they will become sick. All baby kittens need to be fed every 3-4 hours. They also need to be kept nice and warm or they will not eat. A good way to keep a baby kitten warm is to fill a soda bottle with the hottest water you can get, then surround that bottle with blankets and have the kitten sleep there. Baby kittens should be taken to a vet when they are between the ages of 2-3 weeks old. Kittens need to be played with, but, like all babies they can get in trouble and hurt themselves, so they need to be watched closely.
Kittens can be litter box trained at the age of 2-3 weeks old. All you need to do is take something little so the kitten can get in (a little pie pan works great), and fill it with litter. Then when the kitten starts to go, put the kitten in the litter box so it learns to go in there. Most kittens only take a matter of days, sometimes it takes longer, but, it seems that the younger the kitten is the easier it is for it to learn.
See also How to choose your pet and take care of it, which has instructions for caring for adult cats.Birth and development
Caring for kittens