Speaking in tongues, also known as glossolalia, is an activity or practice in which people utter words or speech-like sounds, often thought by believers to be languages unknown to the speaker. One definition used by linguists is the fluid vocalizing of speech-like syllables that lack any readily comprehended meaning. In some cases, as part of religious practice, some believe it to be a divine language unknown to the speaker. Glossolalia is practiced in Pentecostal and charismatic Christianity, as well as in other religions.

Charismatic Christianity is a form of Christianity that emphasizes the work of the Holy Spirit and spiritual gifts as an everyday part of a believer's life. It has a global presence in the Christian community. Practitioners are often called Charismatic Christians or Renewalists. Although there is considerable overlap, Charismatic Christianity is often categorized into three separate groups: Pentecostalism, the Charismatic movement, and the Neo-charismatic movement.