A cat is generally considered a kitten for about the first year of its life. Most kittens are regarded as adult cats when they turn one year old. Larger breeds, such as Maine Coons, may take longer, sometimes up to 18 months to 2 years, to reach full maturity and be considered adults. During their first year, kittens go through rapid development, with significant growth and socialization milestones occurring especially in the first 6 months. After one year, they typically transition to adult cat food and behaviors, although some "adolescent" playfulness may continue up to 18 months before fully settling into adult behavior.