Easter, which celebrates Jesus Christ's resurrection from the dead, is Christianity's most important holiday.
Easter is really an entire season of the Christian church year, as opposed to a single-day observance. Lent, the 40-day period leading up to Easter Sunday, is a time of reflection and penance and represents the 40 days that Jesus spent alone in the wilderness before starting his ministry, a time in which Christians believe he survived various temptations by the devil.