Catechesis (; from Greek: , "instruction by word of mouth", generally "instruction") is basic Christian religious education of children and adult converts to Christianity. As defined in the Catechism of the Catholic Church, paragraph 5 (quoting John Paul II, Apostolic Exhortation Catechesi tradendae 18):

Catechesis is an education in the faith of children, young people and adults which includes especially the teaching of Christian doctrine imparted, generally speaking, in an organic and systematic way, with a view to initiating the hearers into the fullness of Christian life.

In Roman Catholicism, catechists are typically lay ministers trained in the art of catechesis. It might also be a  pastor or priest, religious teacher, or other individuals in church roles (including a deacon, religious brother or sister, or nun). The primary catechists for children are their parents or communities.