Representation of data models via a language specifies essential properties of the real world described by the data. Some of the most popular languages (e.g. entity-relationship model, object data modeling language, unified modeling language) are based around the notions of Abstract Data Types (ADTs), entities, relationships, constraints, and rules. Primitive ADTs specify a domain of possible values, a set of operators and the semantics of operators. Higher level ADTs, e.g., audio, video, images, have a set of simpler attributes and operations (also called methods). Entities (e.g. movies, CD-ROMs, journals, articles, slide-slows, publisher) describe the variety of elements in the digital library. Entities have special attributes, which uniquely identify each instance. Entities have relationships, e.g. a music-video is released by a publisher. Constraints specify restrictions to ensure data integrity, e.g. whether the author of an CD-single can be left blank (anonymous).

Current methods for modeling audio, video and image data can be classified into data-driven and user-driven. Data driven methods use statistical modeling to fit probability distributions, where as user-driven methods take advantage of the peculiarities of human perception. Other data modeling topics relevant to multimedia digital library include spatial and temporal data models.