Definition:
A digital collection consists of digital objects that are selected and organized to facilitate their discovery, access, and use. Objects, metadata, and the user interface together create the user experience of a collection.
Adapted from A Framework of Guidance for Building Good Digital Collections: A NISO Recommended Practice. 3rd ed. National Information Standards Organization: Baltimore, December 2007. / provided by the Center for Digital Initiatives (The University of Vermont Libraries)
Additional Terminology:
Digital Library - broader, may include a number of collections e.g. Digital Library at the Smithsonian, HathiTrust, ARTstor
Digital Collection - materials (documents, multimedia items) selected, gathered and presented onlin e.g. Maps of Los Angeles, California, the United States and the World (Collection 294), The Country Doctor Museum
Digital Archive - narrower? not always a focus on preservation e.g Zora Neale Huston Digital Archive, South Asian American Digital Archive (SAADA)