The third national conference on “Digital Libraries: Processing and Organizing Information and Knowledge” will be held by Department of Information and Knowledge Science of Allameh Tabataba'i University in cooperation with the Iranian Library and Information Association (ILISA) at 17 January 2020. The aim of the conference is exploring knowledge organization and processing systems, conceptual frameworks and conceptual design of knowledge representation, approaches and new methods in the processing and organization of content objects, standards and interoperability Metadata, and the processing of web contents’ organization in national stage. In this regard, all the experts in the related fields, such as planning and developing systems for processing and organizing knowledge, implementing conceptual patterns and modern methods, and coordinating metadata and semantic markup languages, are invited to actively participate in the conference by presenting papers, organizing workshops and also in the scientific sessions.