Speaking in tongues, also called glossolalia, is the practice of making nonsensical, speech-like vocalizations; it is common in several Christian sects including Pentacostalism and Charismatic Christianity. Adherents believe that speaking in tongues is the manifestation of a sacred language made possible by the entrance of the Holy Spirit into the body. Speaking in tongues is referenced several times in the New Testament, in the Gospel of Mark and the books of Acts and Corinthians.
Although speaking in tongues as a church practice is relatively uncommon among mainstream Christian faiths, congregations in the Pentacostal church use verbal expression as an important part of their services. They believe that speaking in tongues is the physical manifestation of being baptized in the Holy Spirit. Xenoglossia is the belief that these unknown tongues are real, unlearned languages that have been briefly bestowed on the speaker through the power of the Holy Spirit.
Cessationists are those who speak in tongues during church services but do not believe the unknown languages they are speaking to be the manifestation of the Holy Spirit. Instead, they believe that speaking in tongues is merely a learned practice or tradition that has been passed down through generations of believers. However, cessationists do believe that the original practitioners of glossolalia in the Bible were under the influence of the Holy Spirit.