Online cataloging in library science refers to the process of creating and managing electronic, machine-readable bibliographical databases, typically accessed through an Online Public Access Catalog (OPAC). This system replaces traditional card catalogs and allows library staff and the public to search for materials online, offering dynamic search options like keyword, author, and title searches. It includes various tools and standards, such as RDA (Resource Description and Access), and integrates with library management systems to provide access to both physical and digital collections.