What is Z39.50?

  • Z39.50 is an international standard protocol used by networked computer systems for information retrieval. 

  • It enables information seekers to search different systems on a network or the Internet through the use of a single user interface.
  • Software and system vendors offer access to information from a diversity of unique systems with different hardware, software, interfaces, and database search command 
  • The goal of Z39.50 is to reduce the complexity and difficulties of searching and retrieving information. 
  • Z39.50 makes it easier to use the wealth of information resources on the Internet. When using Z39.50-enabled systems, a user in one system can search for electronic information in another system without having to know how that system works.

in basic terms, Z39.50 is a network protocol which allows searching of (usually remote) heterogeneous databases and retrieval of data, via one user interface. It is most often used for retrieving bibliographic records, although there are also some non-bibliographic implementations.[*Protocol: a strict set of rules that govern the exchange of information between computer devices.]


  1. Z39.50 is designed to enable communication between computer systems such as those used to manage library catalogues.
  2. the former is undeniably useful to those individuals who have to update things

Real examples of this type of distributed search include the Gateway to the Arts & Humanities Data Service in the UK, and the Melvyl® system of the University of California 

University of California used Z39.50 to gateaway to the art & Humanities Data Services in the UK


  • Z39.50 operates in a client server environment, acting as a common language that all Z39.50-enabled systems can understand. It is an Esperanto-like language that bridges the many “languages and dialects” that different information systems “speak.”

  • Most Z39.50 implementations use the standard TCP/IP Internet communications protocol to connect the systems and Z39.50-compliant software to translate between them for search and retrieval.

  • Z39.50 supports open systems, which means it is non proprietary, or vendor independent. A client system that implements the Z39.50 protocol allows communication with di verse servers, and a server system that implements the protocol is searchable by clients developed by different vendors.

    Niso Press (2002). Z39.50 a primer and the protocol. Date of retrieve 1/8/2011.
    Retrieve from http://www.niso.org/publications/press/Z3950_primer.pdf