TrueType has long been the most common format for fonts on classic Mac OS, Mac OS X, and Microsoft Windows, although Mac OS X and Microsoft Windows also include native support for Adobe's Type 1 format and the OpenType extension to TrueType (since Mac OS X 10.0 and Windows 2000). While some fonts provided with the new operating systems are now in the OpenType format, most free or inexpensive third-party fonts use plain TrueType.