sentences:  Evergreen runs on Linux servers and uses PostgreSQL for its backend database.The staff client used in day-to-day operations by library staff runs on Microsoft Windows, Macintosh, or Linux computers and is built on XULRunner, a Mozilla-based runtime that uses the same technology stack as Firefox and allows for a browser-independent offline mode.The online public access catalog (OPAC) used by library patrons is accessed in a web browser.