Adult is the fifth life stage, between Teen and Senior, that can be unlocked at any level at any point in the game. When players first start up their game, the first Sims they will move in will be an Adult.
General
Adult sims talking to one another
This stage is already unlocked from level 1 onward. This category allows for many things, such as having different types of relationships, work, hobbies and providing money for the household. By finishing the Adulthood quest, players can age their teens to adults.
Adults are the life stage mostly used for the majority of the main and discovery quests in game. Majority of the furniture and hobby items are used mostly by Adults, although some hobby items, like the Finger Painting easel and Teen Idol instruments, are only used by the younger life stages.
Hobbies
Adults doing the Cooking hobby
Adults can do many hobbies, although some are exclusive to the other life stages (for example, bird feeding for Seniors and Ballet for Preteens). Adults can only do one hobby at a time; if they switch to another hobby they will lose their progress on their current hobby and start from level 1. Some hobbies, like Cooking, can have multiple sims.
Examples of hobbies: