An educational, or learning, object can be described as any item used to enhance learning. It could include text and/or images along with web sites, videos, animation, audio, photographs, or presentations. A module or object within an online course, for example, might consist of all of the objects listed above.

To be effective within the context of a repository, learning objects require three main characteristics: accessibility, adaptability and interoperability. First, accessibility (or searchability) refers to the way an object is described and categorized. Second, a user must be able to use and adapt the object without the need to draw upon complex or sophisticated programming or design techniques. Finally, the object should be interoperable, meaning that it should function across a wide variety of hardware, operating systems and web browsers.

In the digital realm, these learning objects are stored on servers and delivered through networks. What pulls these objects together is the structure or organization of the repository. The structure is not a physical thing but rather a set of ideas for organizing the objects.

One way to organize the objects is through metadata. Metadata provides a structure for labeling or "tagging" the objects. One tag might contain the subject matter of the object, another the name of its author or creator.