Eastern Christianity refers collectively to Eastern Orthodoxy and Oriental Orthodoxy, especially when speaking more about what they share in common than about the ways they differ. The term may also include Eastern-Rite Catholic churches, which are those branches of Roman Catholicism -- including only about 2% of Catholics -- that are subject to the eastern Catholic patriarchs. They follow rules and customs similar to those of Eastern Orthodox churches; for example, their priests need not be celibate and their parish priests administer the sacrament of confirmation to newborn infants immediately after baptism via the rite of chrismation.
Historically, Western Christianity developed in Europe, whereas Eastern Christianity developed in the Near East. Today, however, the geographical distinction is not nearly as absolute.