Document description and coding are key operations to information storage and retrieval systems. Description makes it possible for users to obtain information about the documents while coding provides unique numbers to described documents, and enables users to locate, retrieve and store documents manually or electronically. Consequent upon the mass production of information and attendant information explosion, modern libraries and other information dissemination institutions, attached to various institutions, were established. A need therefore arose to put in place systems of achieving bibliographic control over the information produced and collected to facilitate its identification and location wherever it may be found. Among the major systems or tools that information professionals developed to achieve bibliographic control and organization of information include: cataloguing, classification, indexing and abstracting. Using largely documentary sources, the chapter makes a case on the critical role of document description and coding systems in information and knowledge management.