The Greenstone digital library software is a comprehensive system for building and distributing digital library collections. It provides a way of organizing information based on metadata and publishing ti on the Internet. This paper introduces Greenstone and explains how librarians use it to create and customize digital library collections. Through an end-user interface, they add documents and metadata to collections, create new collections whose structure mirrors existing ones, and build collections and put them in place for users to view. More advanced users can design and customize new collection structures