Religions typically have particular practices in which people engage. The form of these practices varies greatly and may include such activities as worship, preaching, prayer, meditation, confession, sacrifice, offerings, rites of passage and other sacred ceremonies. Sometimes these practices are quite elaborate and publicly visible, as in the eucharistic liturgy of the Eastern Orthodox Church or the sacred ceremonies of Australian aboriginal religions. Sometimes they are much less elaborate and less publicly visible, as in the forms of meditation practised in Buddhism or the private prayer which is part of various religious traditions. In using the word "ritual" to describe such activities one does not necessarily imply that there is a precisely specified form which the practices must take, nor does one necessarily imply that people undertake these activities simply out of habit. In many forms of ritual there is both an outer (or visible) and inner (or non-visible) aspect.