The association of a Persistent Identifier to a digital resource is a best practice helping in solving a reliable information resources retrieving on the web. At the present moment, different kind of technologies and standards such as DOI, Handle are establishing. However, within scientific and cultural communities, the main need is still focused on ensuring resources authenticity, provenance, and preservation in the long term period. For this reason, a third authoritative party such as the National Library is necessary, managing identifiers and process requirements for preservation aims. The NationalBibliographyNumber originated in the context of the role and the responsibilities of national libraries in the field of universal bibliographic control, oriented to the identification of resources to be preserved in the long period. In Italy NBN:IT is going to be linked to the legal deposit, and activity traditionally up to the national libraries guaranteeing its trustability. The project, coordinated by the national libraries of Florence, Rome, and Venice, by the Foundation Rinascimento Digitale and by the Conference of Rectors of the Italian Universities, completes the current offer of PI. Today we have assigned almost 10.000 NBN:IT. Plugins for the main repository software as DSpace, Eprints, Ojs were released.