Luther's Small Catechism (Der Kleine Katechismus) was written by Martin Luther & published in 1529 for the training of children. The Small Catechism reviews the Ten Commandments, the Apostles' Creed, the Lord's Prayer, the Sacrament of Holy Baptism, the Office of the Keys & Confession & the Sacrament of the Eucharist. It's included in the Book of Concord as an authoritative statement of what Lutherans believe. The Small Catechism is widely used today in Lutheran churches as part of youth education & Confirmation.