Survivors

The people in your fort are called survivors. They may be assigned to various missions (including forced ones such as recovering from an injury) and constitute the entirety of your fort's workforce. Survivors not assigned to any other mission default to the "Guard" mission (more often than not at a spot that does not require guarding, so keep an eye out for slackers). When assigning survivors to a mission via a list the ones on the guard duty will be found at the top of the list. In a sense, the game treats them as "idle" workforce.

Unless they have a camper perk, each survivor needs a home to live in. Unless changed by perks or policies, each will consume 1 unit of food per day. They also each have a happiness level ranging from 0 to 100.

Having no free housing will prevent recruitment. IIRC having more people than houses (for example by losing a house to zed) will result in a hit to happiness. Starvation will result in a hit to happiness and in injuries from starvation events. Low happiness will result in various negative events.

Every survivor (other than MC) has a current "class" corresponding to one of the 5 skills (used mostly for determining which of the 5 skills can currently be trained), has a both a "native" level in each of the 5 skills (determined by training) and an "effective" level (determined by training, perks and equipment).

Each survivor can be equiped with up to 2 items of equipment one from each category, the two categires being "weapons" and "everything else". The former includes only things considered to be weapons (though the defenition is loose, as expected from the setting), and the latter includes tools, headgear, books, vehicles, pets and children (did I miss anything here?).

Survivors can also accquire perks. Up to 3 can be selected as their native skill levels rise, and more can be gained as bonus perks (the extra starting ones on new recruits, the ones earned in events, and the temporary ones granted by equipment).

New survivors can be acquired through recruitment missions, sometimes appearing through random events whose occurrence can be increased or decreased based on research and policy, and by destroying factions you have the option of recruiting 2 unfortunate survivors, also some of the plotlines can result in recruiting some specific survivors. Some of the new recruits may come with training or equipment, but most of them will lack both.

Some recruited survivors may have children with them, and heterosexual couples in your fort will sometimes produce kids of their own. Children consume half a unit of food every day. Unless the fort's "Children must go to school" policy is in effect, each child must be equipped by a survivor or the game will automatically assign a survivor to equip the child. Once equiped they act as a burden for the character who looks after them, reducing all of their effective skills by one. Each child has an instant hint that shows their age, which will increase as the game goes on (at an accelerated rate, no need to wait for several thousands of days), at 14 the child grows up and becomes a full-fledged survivor in your fort. It is also worth noting that only children have age, adult survivors do not.