Library is a collection of various types of materials in different forms and formats containing and generating lots of data. Library is a system that consists of inter-dependent and interrelated sub-systems that generate huge amounts of data and share the common data within the system and across the systems. In modern integrated library systems, the bibliographic data is primarily connected to various other sub-systems. The back-end relational database management systems (RDBMS) are effective in organizing the data in standard formats avoiding data redundancy and thereby facilitating to share the same as per standard protocols. The data so created for processing is shared for further processing of library in-house operations that which is usually made available to users for their retrieval. Thus, the entire cycle revolves around the growing information requirements of users and structuring the library databases according to transforming data, their forms and formats. The library data needs are unlimited and cannot be estimated as the pattern of retrieving information by users varies with the context and also to support the managerial decisions. However, libraries need to handle them in the current scenario. The book attempts to focus on creating and understanding the basic concepts of databases, library databases, DBMS/RDBMS functioning at the backend of LIS operations in building such databases while specifying the usefulness of DBMS approach in the effective retrieval of information from library catalogs as well as from external online databases. The relevant strategies to be applied in information retrieval and useful tools are briefly dealt referring the emerging trends in library data management.