Adult

Adult is a life stage in The Sims, The Sims 2 and The Sims 3. In The Sims and The Sims 2, it is the longest life stage in a Sim's life. In The Sims 3, it is the same length as the Young Adult life stage. In this stage, Sims can have or adopt children and start a family of their own.

The Sims
In The Sims, being an adult is permanent, as they never get older. Their lifespan is indefinite and they need to be killed in order for them to die.

Adult Sims can take up jobs, fall in love, have and raise children, and prepare food, while children cannot. Obviously, it is nearly impossible for a family to function without adults.

Adult Sims can use most of the objects in the game and most of the interactions with other Sims.

The Sims 2
In the Sims 2, the adult stage is the longest and most important life stage. It is the only life stage in which your Sim can get pregnant (sometimes, even if your Sim is a male, after getting abducted by Aliens) and get a normal job. In the Freetime expansion pack, your Sim can study up on parenting via the book case. The adult stage lasts 29 days, but adult Sims can drink the Elixir of Life to slow down the aging process.

The Sims 3
In The Sims 3 the Adult stage is no longer the default age. Young Adult is now the default age in Create-A-Sim. Adults in The Sims 3 can be considered more like adults in their 'Middle-age'. They are roughly 30-60 years old. They get a few wrinkles, but they aren't as pronounced as they are in the Elder stage. There's not much difference between an adult and Young Adult; they can still get married and have children. However, young adults are more fertile, which means it takes less tries to get a Young Adult sim pregnant. Like Young Adults, they have the option to get a full-time or part-time job.

Adults have the same 5 traits they had as a Young Adult and it takes 21 days (on the normal life span setting) to progress to the Elder stage.

Things that Adults can do that younger sims can't:
 * Have minor wrinkles