Villagers are the people that live on the islands. They are the people being controlled by the player, who is supposed to make the villagers' lives easier.
Age is a big factor in the villagers' output. It determines what the villager can and cannot do.
An infant is the child that is still being cared for by the family. The infant doesn't have its own Details page, as it is only shown in the photo of the mother carrying the infant. Therefore, it is unable to determine name, gender, abilities, preferences and health (an infant cannot get sick apparently) of the infant yet, but his/her age is surely below two years old. The infant cannot do anything yet, so the mom and dad will spend all of her time on caring for the infant.
Children are villagers with the ages 2-13 years old. A child cannot work yet, so he/she will not farm, build, research, heal and breed definitely no matter what the player does. However, it can do certain functions that adults cannot, like picking up mushrooms, which contribute to the food supply, and starting Virtual Villagers 2: The Lost Children, they can also pick up collectibles. When left alone and they're not playing, dancing or answering nature's call, they might be curious about something which could contribute help to Puzzles.If an adult villager is dropped on a child, the adult will start telling a story while all of the children and teenagers will start listening. Children's speed are always quick, unless they dislike running. Children can get sick.
Teens are villagers with the ages 14-18 years old. They can work such as farming, building, research and healing, but they cannot reproduce yet. If an adult villager is dropped on a teen, the adult will start telling a story while all of the children and teens will start listening. Teens can get sick.
Adults are villagers with the ages 19-50/55 years old (depending on the game). They can work and reproduce, They can run if they like running, but they dislike it, their speed is very slow.
Elderly villagers have ages of 50/55 and above. They can work and reproduce (though the elderly females will no longer receive babies from a stork), but they are more likely to go lazing around. They are easily weakened, and require more care and caution. Their speed is automatically slow. If they like running, they just become medium speed.