All Souls' Day is a day to remember and pray for people who have died. It's like going to visit someone who isn't here anymore to say hello and tell them that you miss them.
Some people believe that when a person dies, their soul goes either to heaven or to purgatory. Heaven is a happy place where people are with God, and purgatory is a place where people wait to enter heaven.
On All Souls' Day, people go to church and light candles for their loved ones who have died. They may also pray for other souls who are in purgatory and need help getting to heaven. It's a way to show love and respect for those who have gone before us.
It's a sad day for some people because they miss their loved ones, but it's also a day to remember happy memories and be grateful for the time they had together.