Technically a catechism,"to teach orally", is the summary or exposition of doctrine used in catechesis rather than a printed document. That has been the case since the Apostles, who had catechumens (those undergoing catechesis) who wished to become Christians.

Since documents were handwritten and not all were literate, these were often in the form of simple texts that could be memorized along the lines of the Apostles’ Creed.

When printing became available, small books of instruction appeared. The use of a question and answer format was popularized by Martin Luther in his 1529 Small Catechism.

While called a catechism, the Catechism of the Council of Trent published in 1566 was not for the laity but a reference book for priests and bishops. Trent was NOT the first Council where doctrines were defined.