The management of information resources has been greatly influenced over the last decade by the widespread use of electronic documents. This change has forced libraries, archives and documentation centers to manage a new type of materials and become familiar with the new formats and c on the tools and technologies necessary for their treatment. Among these, markup languages​​, and in particular the xml format, have become a major tool in various desktop publishing programs and metadata management. This work aims to provide the user with a detailed analysis of the characteristics of markup languages ​​and their main applications in libraries and archives knowledge. To do this, applications developed in recent years for the management of metadata (MODS, METS, Dublin Core), authority records (MADS, EAC), content encoding (TEI), description of the archive (EAD) are described digital Preservation (Tubes) and information retrieval (OAI, ZING SRW / SRU). The book also aims to serve as a reference work for the main types of documents designed with a view to libraries and archives.