The increasing desire by researchers to have easy access to HPC services, and the objective to follow FAIR data access (Findable, Accessible, Interoperable, and Reusable), guided PRACE-6IP WP6 to identify common rules to provide resources in a more user-friendly way. The following white paper describes policies and architecture of an authentication and authorization infrastructure (AAI) agreed by PRACE-6IP partners. In 2019, PRACE-6IP WP6 was tasked to define a plan for more user-friendly and forward-looking services for the future. PRACE AAI was one of the results of this activity and a first pilot and a demo were released in May 2022 (section “Architecture and Pilot”). The aim was to provide user-friendly access to PRACE services. This document describes the agreed policies to release the service. Additionally, the document describes the policies about how to provide a trustable PRACE IdP (Identity Provider) to PRACE users to facilitate the access to non-PRACE services. The work has been done in collaboration with Fenix, and this document has been partially inspired by work done in the ICEI project, and by the AARC Blueprint Architecture.