Palm Sunday marks the beginning of Holy Week and commemorates Jesus' triumphant entry into Jerusalem, when crowds waved palm branches and shouted 'Hosanna!' (Matthew 21:1-11). At Mass, the faithful receive blessed palm branches and participate in a procession re-enacting this event. The Mass then transitions dramatically to the reading of the Passion narrative — the full account of Jesus' arrest, trial, suffering, and death. This contrast between triumphal entry and crucifixion is intentional, showing how quickly the crowd turned from 'Hosanna' to 'Crucify him!' Catholics traditionally keep blessed palms in their homes throughout the year. The following year, these palms are burned to create the ashes for Ash Wednesday.