In ancient Greek, pentekoste meant "fiftieth day"—that is, the fiftieth day after Easter (counting Easter itself). On that day, Christians celebrate an event described in the Bible that took place fifty days after Christ's resurrection, when the apostles heard the rush of a mighty wind, saw tongues of fire descending on them, and heard the Holy Spirit speaking from their own mouths but in other tongues (languages). "Speaking in tongues", when everyone in a congregation may begin talking in languages that no one can understand, is the best-known practice of Pentecostals. Pentecostals belong to many different denominations; with growing numbers especially in Latin America and Africa, there may be over 500 million Pentecostals worldwide.