The Season of Easter begins on Sunday, April 5. It will run for seven weeks. Easter is a time of celebration and thanksgiving for the victory of Christ over death and sin. Jesus was present in his resurrected form for 40 days before he ascended into heaven right in front of his disciples' eyes. Jesus instructed the disciples to wait in Jerusalem for the gift of the Holy Spirit.
Seven Sundays after Easter, on May 24, we celebrate Pentecost, the birth of the church. It is the day on which the Holy Spirit descended upon the disciples, they were filled with the ability to speak in other languages, and people from all over the Mediterranean region visiting in Jerusalem that day, heard the good news of Jesus being shared in their own language. It was such a miracle that 3,000 people committed their lives to following Christ and they were baptized that day. From that day on, these folks met in homes every evening and shared meals and stories of Jesus with the new converts.
The remaining weeks of summer are called "Ordinary Time."