Passover (Greek "ta pascha", the root of our word Paschal) was the annual Jewish family celebration remembering God’s deliverance of Israel from Egypt by striking down every Egyptian firstborn, both children and animals, and “passing over” those of the Hebrews who marked their doors with blood from their sacrificed lambs.
The most ancient and always the central event of the liturgical year is the Easter Triduum (Latin, "three days") celebrating the passion, death and resurrection of Christ. The sacred three days (Holy Thursday, Good Friday and Holy Saturday) are a liturgical season in themselves and not strictly part of Lent.
The Easter Vigil echoes the early Christian ritual that lasted through the night to celebrate the eucharist at dawn. It’s four parts are: lighting the Easter/Paschal candle; listening to the scripture readings of the story of salvation; initiating the new converts into the Church community; and, ending in the Eucharistic celebration.
This year our Easter or Paschal candle is called Imperat, reflecting what we sing in the popular hymn, “To Jesus Christ our Sovereign King.” We sing a translation of ‘Christus vincit, Christus regnat, Christus Imperat.’ The Paschal Candle “a symbol of the presence of the Risen Christ among the people of God,” is lit and shines at all our liturgies, remaining near the altar or lectern for these 50 days, until Pentecost.