Some funding agencies require that published research results enabled by their grants be made available to the general public, usually on the internet.
Public access mandates generally apply to journal articles whose publication is a direct result of research performed under the grant as well as to research data generated during, or as a result of, the research process (with some exceptions and limitations).
UW-Madison Public Access Compliance Resources
Research Data Services
Vice Chancellor for Research & Graduate Education
Vice Chancellor for Finance & Administration