Pederasty describes a relationship between an older and younger man, typically of a consensual, sexual nature. In Ancient Greece, the practice of pederasty was quite common and heavily tied to education and training. An older, well-established man would form a romantic relationship with a boy who was somewhere between the ages of twelve and eighteen. This relationship was more a dynamic of master and apprentice than a romantic couple, and the older man was at least partly responsible for the education, socialization, and skill training of his younger partner. In some parts of Greece, the older man would also provide gifts to his younger partner to help him establish a life. One such tradition involved presenting the young man with military clothing as a gift to begin his military training.
Though such a relationship strikes discomfort in the heart of many a modern person, it is important to note that these relationships were fundamentally different from pedophilic behavior. The pederastic relationship involved much more than sexual intimacy, and though there was an age-based power dynamic involved, the younger partner is understood to have consented to the relationship. Some historians debate the degree of consent or affection involved in pederasty, but we can glean knowledge from the term itself. The root word erastes translates as "love" or "lover" and was used in terms describing relationships of both hetero- and homosexual natures. In contrast to the nurturing and romantic connotations of pederasty, pedophilia is a pathological, consumptive, and abusive sexual impulse which has no regard for whether a younger partner consents.
In short, the pederastic relationships of Ancient Greece were not only romantic or sexual, but also involved the tutelage and training of a younger man by someone who was older and more experienced.