An institutional repository is "...a set of services that a university offers to members of its community for the management and dissemination of digital materials created by the institution and its community members." (Lynch, 2003, p. 2)
A good example of an institional repository is DRUM at University of Maryland, College Park.
As per the CRL (Center for Research Libraries), librarians and other information science professionals have identified the necessary elements to a "trusted digital repository." See the CRL links in the resources section for metrics, documentation, and the "ten principles" that are essential. For the record, not every digital repository will fit these standards to a "T" but they are goals to strive for.
Center for Research Libraries. Metrics for Repository Assessment. Retrieved from http://www.crl.edu/archiving-preservation/digital-archives/metrics-assessing-and-certifying
* Center for Research Libraries. Ten Principles. Retrieved from http://www.crl.edu/archiving-preservation/digital-archives/metrics-assessing-and-certifying/core-re
* Lynch, C. (2003, February). Institutional repositories: Essential infrastructure for scholarship in the digital age. ARL Bimonthly Report 226, 1-7. Retrieved from http://www.cni.org/wp-content/uploads/2003/02/arl-br-226-Lynch-IRs-2003.pdf.
Nabe, J. A. (2010). Starting, strengthening, and managing institutional repositories: A how-to-do-it-manual. New York, NY: Neal-Schuman Publishers, Inc.
Campbell-Meier, J. (2008). Case studies on institutional repository development: creating narratives for project management and assessment (Doctoral dissertation). Retrieved from http://scholarspace.manoa.hawaii.edu/handle/10125/4177 and http://hdl.handle.net/10125/4177
Bruns, T. (2013, November). The Keep at two: The first two years of our institutional repository. Retrieved from http://works.bepress.com/todd_bruns/36/
- Points of interest on document pages 9, 13, 15, 27, and 28.
Eastland, K., & Neatrour, A. (2007, November/December). Utah Digital Repository Initiative: Building a Support System for Institutional Repositories. D-Lib Magazine, 13(11/12). Retrieved from http://www.dlib.org/dlib/november07/neatrour/11neatrour.html
Royster, P. (2009, October). Case Study: DigitalCommons@University of Nebraska–Lincoln. Faculty Publications, UNL Libraries, Paper 264. Retrieved from htp://digitalcommons.unl.edu/libraryscience/264