What is Easter? What do Christians Celebrate on Easter?

On Easter Sunday, Christians celebrate the resurrection of the Lord, Jesus Christ. It is typically the most well-attended Sunday service of the year for Christian churches.
Christians believe, according to Scripture, that Jesus came back to life, or was raised from the dead, three days after his death on the cross. As part of the Easter season, the death of Jesus Christ by crucifixion is commemorated on Good Friday, always the Friday just before Easter. Through his death, burial, and resurrection, Jesus paid the penalty for sin, thus purchasing for all who believe in him, eternal life in Christ Jesus.