The age at which someone is classified as an adult varies from one culture or country to another, but is usually set at age 18 or 21. Though they're no longer growing, adults go through developmental stages, just as children do. This list includes adult health and adult education sites, as well as dating sites for adults. The term "adult" is often used to tag pornographic websites. AboutUs.org aims to exclude adult content from the site. Please add any useful sites about the adult state of being, along with a short summary for each.