A catechism is a summary of doctrine, traditionally used in Christian religious teaching from New Testament times to the present.

Catechisms are doctrinal manuals often in the form of questions followed by answers which have been memorised.

Here is an example. It is called the 19th century Roman Catholic Baltimore Catechism:

Q. What rule hath God given to direct us how we may glorify and enjoy him?

A. The word of God contained in the Old and New Testaments is the only rule that is to direct us how we may enjoy him.