While the word religion is difficult to define, one standard model of religion used in religious studies courses defines it as
[a] system of symbols which acts to establish powerful, pervasive, and long-lasting moods and motivations in men by formulating conceptions of a general order of existence and clothing these conceptions with such an aura of factuality that the moods and motivations seem uniquely realistic.
Many religions have narratives, symbols, traditions and sacred histories that are intended to give meaning to life or to explain the origin of life or the universe. They tend to derive morality, ethics, religious laws, or a preferred lifestyle from their ideas about the cosmos and human nature. According to some estimates, there are roughly 4,200 religions, churches, denominations, religious bodies, faith groups, tribes, cultures, movements, ultimate concerns, which at some point in the future will be countless.
The word religion is sometimes used interchangeably with the words "faith" or "belief system", but religion differs from private belief in that it has a public aspect. Most religions have organized behaviours, including clerical hierarchies, a definition of what constitutes adherence or membership, congregations of laity, regular meetings or services for the purposes of veneration of a deity or for prayer, holy places (either natural or architectural) or religious texts. Certain religions also have a sacred language often used in liturgical services. The practice of a religion may also include sermons, commemoration of the activities of a God or gods, sacrifices, festivals, feasts, trance, rituals, liturgies, ceremonies, worship, initiations, funerals, marriages, meditation, invocation, mediumship, music, art, dance, public service, or other aspects of human culture. Religious beliefs have also been used to explain parapsychological phenomena such as out-of-body experiences, near-death experiences, and reincarnation, along with many other paranormal and supernatural experiences.