First off…
TODAY IS A HOLY DAY OF OBLIGATION. IF YOU’RE READING THIS YOU CAN’T PRETEND YOU FORGOT OR DIDN’T KNOW.
IF YOU MISS MASS TODAY WITHOUT A LEGITIMATE REASON, IT IS A GRAVE SIN AND YOU MUST GO TO CONFESSION BEFORE RECEIVING COMMUNION AGAIN.
All Saint’s Day is usually associated with the saints recognized by the Church, but really it is a day to honor all the holy men and women who are now in heaven, not just those who have been officially canonized. This is an article by Catholic Restoration explaining this day in depth.
Lumen Fidei Ministries 