Summorum Pontificum: Two Forms of the Roman Rite

Pope Benedict XVI, in 2007 issued an Apostolic Letter motu proprio under the title Summorum Pontificum together with a note which explains:

“The fundamental provision is as follows: the Roman liturgy will have two forms:

1. The ordinary form is the one that follows the liturgical reform undertaken by Pope Paul VI in the year 1970, as it appears in the liturgical books promulgated at that time. There is an official edition in Latin which may be used always and everywhere, and translations in divers languages published by the various episcopal conferences.
2. The extraordinary form: which is that celebrated in accordance with the liturgical books published by Blessed Pope John XXIII in 1962.”