Ephebophilia is the sexual preference of an adult for post-pubescent adolescents. It is also used as meaning the exclusive sexual attraction to post-pubescent adolescents.
It is distinct from the attraction to children (defined as pre-pubescent people), which is pedophilia. It is also sometimes confused with, or wrongly inclusive of, Hebephilia, which is the sexual attraction to people going through puberty.
What defines an adolescent, and therefore what defines an ephebophilic relationship, varies between jurisdictions, and along with that, the legality of ephebophilia.
Sexual desire that includes adolescents, as well as older individuals, is common among adults of all sexual orientations. In some cultures, such as those in which adolescent girls are routinely married to older men, it is considered normal for adults to include adolescents among their sexual interests. In other cultures, it can be illegal to act upon such feelings.
As in all legal matters, please do not rely on Wipipedia but consult a legal professional.
Attraction to adolescents is not generally regarded by psychologists as pathological except when it interferes with other relationships, becomes an obsession which adversely affects other areas of life, or causes distress to the subject. Ephebophilia is not listed in the ICD-10 (International Statistical Classification of Diseases and Related Health Problems) or the DSM IV (the American Diagnostic and Statistical Manual).