What significant event is celebrated on the Day of Pentecost in the Christian tradition?

The Day of Pentecost is celebrated in Christian tradition as the occasion when the Holy Spirit was poured out on the disciples of Jesus, marking the birth of the Church. This significant event occurred fifty days after Easter, following Jesus' ascension into heaven. The apostles were gathered together when they experienced a powerful sound like a rushing wind, and they were filled with the Holy Spirit, enabling them to speak in various languages. This outpouring empowered them for ministry and mission, leading to the conversion of about three thousand people that day. The Day of Pentecost thus holds profound importance as it fulfills Jesus' promise of sending the Holy Spirit to guide, empower, and teach the followers of Christ.