Today is Divine Mercy Sunday. This day is celebrated every year on the Sunday after Easter. As recorded in Saint Faustina's Diary, Jesus asked for this day to be acknowledged worldwide so that the ocean of His Divine Mercy may be opened to everyone on this day. Everything He does for humanity, whether it be just or merciful, He does out of love. After death, we are subject to God's justice becuase it is too late for us to repent. He wants us to receive His mercy while we still can.
"I saw an Angel, the executor of God's wrath... about to strike the earth...I began to beg God earnestly for the world with words which I heard interiorly. As I prayed in this way, I saw the Angel's helplessness, and he could not carry out the just punishment...."
These words are found in the Diary of Saint Faustina. This Diary, btw, has been sold to millions worldwide. It is a very powerful book.
As part of today's feast, there is a plenary indulgence (your soul is no longer stained with sin if you do this indulgence). This indulgence entails that you have your confession heard, receive the Eucharist, and say the Chaplet of Divine Mercy.
It is a simple, beautiful indulgence that Christ asked of us, and the benefits are abundant.