Since the first release of open data from an LHC experiment by CMS in 2014, the CMS
Open Data program has matured into a sustained pipeline of data to the public. These
data, several petabytes of real and simulated collisions, have found extensive use in
educational programs as well as in the larger research community. In these proceedings
we describe the content of CMS Open Data and the policy framework that governs its
release, review how the data have been used for education and for research, and discuss
the challenges and opportunities that lie ahead for data preservation and open access
in CMS.

