Prayer is an invocation or act that seeks to activate a rapport with an object of worship through deliberate communication. In the narrow sense, the term refers to an act of supplication or intercession directed towards a deity (a god), or a deified ancestor. More generally, prayer can also have the purpose of thanksgiving or praise, and in comparative religion is closely associated with more abstract forms of meditation and with charms or spells.Prayer can take a variety of forms: it can be part of a set liturgy or ritual, and it can be performed alone or in groups. Prayer may take the form of a hymn, incantation, formal creedal statement, or a spontaneous utterance in the praying person.
The act of prayer is attested in written sources as early as 5000 years ago. Today, most major religions involve prayer in one way or another; some ritualize the act, requiring a strict sequence of actions or placing a restriction on who is permitted to pray, while others teach that prayer may be practised spontaneously by anyone at any time.
Scientific studies regarding the use of prayer have mostly concentrated on its effect on the healing of sick or injured people. The efficacy of prayer in faith healing has been evaluated in numerous studies, with contradictory results.