This paper discusses the Z39.50 protocol. The ANSI/NISO Z39.50 protocol for information retrieval addresses the complex challenges of intersystem communication. Original uses envisioned for the protocol look very little like current implementations and uses. In the 1980s, users on one library catalog system would search and retrieve bibliographic records on a remote system. By the late 1990s, there was a need for discovering networked resources and integrating access to them. Yet, the Z39.50 protocol has addressed both these scenarios. This paper provides a portrayal of Z39.50 that explains its flexibility in response to a variety of information retrieval requirements in the networked environment.