A learning object can be defined as "any entity, digital or non-digital, that may be used for learning, education or training" .
A learning object is "any digital resource that can be reused to support learning" .
A learning object is "A digital self-contained and reusable entity, with a clear educational purpose, with at least three internal and editable components: content, learning activities and elements of context. The learning objects must have an external structure of information to facilitate their identification, storage and retrieval: the metadata.".
Learning objects have the following key characteristics: Learning objects are a new way of thinking about learning content. Traditionally, content comes in a several hour chunk. Learning objects are much smaller units of learning, typically ranging from 2 minutes to 15 minutes. Are self-contained – each learning object can be taken independently Are reusable – a single learning object may be used in multiple contexts for multiple purposes Can be aggregated – learning objects can be grouped into larger collections of content, including traditional course structures Are tagged with metadata – every learning object has descriptive information allowing it to be easily found by a search. 
- Learning Technology Standards Committee (2002), Draft Standard for Learning Object Metadata. IEEE Standard 1484.12.1, New York: Institute of Electrical and Electronics Engineers.
- Wiley, David A. (2000), "Connecting Learning Objects to Instructional Design Theory: A Definition, A Metaphor, and A Taxonomy", in Wiley, David A. (DOC), The Instructional Use of Learning Objects: Online Version.
- Rehak, Daniel R.; Mason, Robin (2003), "Engaging with the Learning Object Economy", in Littlejohn, Allison, Reusing Online Resources: A Sustainable Approach to E-Learning, London: Kogan Page, pp. 22-30.
- Chiappe, Andres.; Segovia, Yasbley; Rincon, Yadira (2007), Educational Technology Research and Development, Boston: Springer, pp. 671-681, (http://andreschiappe.blogspot.com.au/2007/09/que-es-un-objeto-de-aprendizaje-what-is.html). (retrieved Jan 20, 2011)
- National digital learning resources network (retrieved Jan 20, 2011)
- AGORA Teachers' Centre
A publicly accessible online learning environment at the Virtual Museum Canada. (retrieved Jan 20, 2011)
- MERLOT (Multimedia Educational Resource for Learning and Online Teaching)
A free and open resource designed primarily for faculty and students of higher education. (retrieved Jan 20, 2011)
- Preparing teachers to use learning objects
Bratina, T., Hayes, D. and Blumsack, S. ( ) Preparing Teachers To Use Learning Objects. (retrieved Jan 20, 2011)