Prayer is the act of attempting to communicate with a deity or spirit. Purposes for this may include worshipping, requesting guidance, requesting assistance, confessing sins, as an act of reparation or to express one's thoughts and emotions. The words of the prayer may take the form of intercession, a hymn, incantation or a spontaneous utterance in the person's praying words. Secularly, the term can also be used as an alternative to "hope". Praying can be done in public, as a group, or in private. Most major religions in the world involve prayer in one way or another. The efficacy of prayer as a petition to a deity is usually evaluated with regard to the concept of prayer healing. There have been numerous studies done, with contradictory results. There has been some criticism of the way the studies were conducted.