The egg itself became a symbol of the Resurrection. Just as Jesus rose from the tomb, the egg symbolized new life emerging from the eggshell. In the Orthodox tradition, eggs are painted red to symbolize the blood that Jesus shed on the cross. The egg-coloring tradition has continued even in modern secular nations.
The tradition of dyeing and decorating Easter eggs is ancient, and its origin is obscure, but it has been practiced in both the Eastern Orthodox and the Western churches since the Middle Ages. The church prohibited the eating of eggs during Holy Week, but chickens continued to lay eggs during that week, and the notion of specially identifying those as Holy Week eggs brought about their decoration.
Easter is the principal festival of the Christian church, a celebration of the Resurrection of Jesus Christ on the third day after his Crucifixion.