More than 15 years after its initial appearance, the electronic resources knowledge base has come into its own as a tool that touches nearly every area of library management. And the knowledge base continues to evolve, expanding into areas such as APIs, open data, community contribution models, and integration with next-generation systems. This issue of Library Technology Reports analyzes the impact of knowledge bases on library management practices and explores new directions and trends for these tools. Inside, Wilson traces the evolution of the knowledge base; provides context for knowledge base creation and maintenance; addresses the emergence of community-managed, open source, and national knowledge bases; and explores areas of innovation, including use in library services platforms, integration with external tools and services, and collaborative knowledge base projects .