Digital Item is the basic unit of transaction in the MPEG-21 framework. It is a structured digital object, including a standard representation, identification and metadata.

A Digital Item may be a combination of resources like videos, audio tracks or images; metadata, such as descriptors and identifiers; and structure for describing the relationships between the resources.

It is becoming difficult for users of content to identify and interpret the different intellectual property rights that are associated with the elements of multimedia content. For this reason, new solutions are required for the access, delivery, management and protection of this content.

MPEG-21 proposes to facilitate a wide range of actions involving Digital Items so there is a need for a very precise description for defining exactly what constitutes such an item.

A Digital Item Declaration (DID) is a document that specifies the makeup, structure and organisation of a Digital Item. The purpose of the Digital Item Declaration is to describe a set of abstract terms and concepts, to form a useful model for defining what a Digital Item is. Following this model, a Digital Item is the digital representation of an object, which is managed, described or exchanged within the model.