Institutional repositories implemented at educational and research institutions allow authors to deposit the content they produce while at that institution into a repository based on open standards so their content is interoperable and widely disseminated on the web. Most are committed to sustainability and long-term access to their content.
Examples of long-standing institutional repositories:
Subject, or disciplinary repositories, and specialized repositories also have a long history. Merits of these subject-based or specialized repositories are that they are tailor-made by experts in a field and are targeted for a specialized group of users so features can be developed accordingly. Some repositories are format based like Dataverse (Harvard), an open source research data repository. They are generally open to authors with any or no institutional affiliation, examples:
SHERPA/RoMEO (Publisher copyright policies & self-archiving)