What is an Institutional Repository (IR)?

An IR collects, preserves, and disseminates the intellectual output of an institution in digital form. Institutional repositories are accessible to end users both within and outside of the institution, ideally with no barriers to access.

Adapted from: http://www.arl.org/sparc/bm%7Edoc/ir_final_release_102.pdf and http://en.wikipedia.org/wiki/Institutional_repository