HathiTrust is a large-scale collaborative repository of digital content from research libraries including content digitized via the Google Books project and Internet Archive digitization initiatives, as well as content digitized locally by libraries. In October 2015, HathiTrust comprised over 13.7 million volumes, including 5.3 million of which were in the public domain in the United States. HathiTrust provides a number of discovery and access services, notably, full-text search across the entire repository.