This contribution seeks to present the modus operandi of the Apostolic Penitentiary, the Tribunal of the Roman Curia that is responsible for everything relating to the internal forum and the granting of indulgences. To do this, reference is made first of all to the notion of the internal forum so as to then illustrate the responsibilities attributed to the Apostolic Penitentiary by the recent apostolic constitution Praedicate Evangelium of Pope Francis. Attention is then paid in particular to the delicts reserved to the Holy See and the way a confessor should behave towards a penitent who has incurred excommunication. Lastly, a reference is also made to the other responsibilities of the Apostolic Penitentiary relating to dispensation from irregularities and the granting of other graces, with references to the works indicated in the bibliography provided for further reading.