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, other than the Internet Error 404. At the present moment, different kind of technologies and standards such as DOI, Handle, and Cool URI are establishing. However, within scientific and cultural communities and in the semantic web, the main need is still focused on ensuring resources authenticity, provenance, and preservation in the log term period. For this reason, a third authoritative party such as the National Library is necessary, managing identifiers and taking in consideration technical as well as community and process requirements for preservation aims. The National Bibliography Number (NBN) 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 acrivity 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 Persistent Identifiers.
