X.Org Server
X.Org Server is the free and open source implementation of the display server for the X Window System stewarded by the X.Org Foundation.
Implementations of the client side of the protocol are available e.g. in the form of Xlib and XCB.
The services with which the X.Org Foundation supports X Server include the packaging of the releases; certification (for a fee); evaluation of improvements to the code; developing the web site, and handling the distribution of monetary donations. The releases are coded, documented, and packaged by global developers.
Software architecture
The X.Org Server implements the server side of the X Window System core protocol and extensions to it, e.g. RandR.
Version 1.16.0 integrates support for systemd-based launching and management which improved boot performance and reliability.
An X server has a tremendous amount of functionality that you must support to claim to speak the X protocol. This includes code tables, glyph rasterization and caching, XLFDs, and the entire core rendering API that lets you draw stippled lines, polygons, wide arcs and many more state-of-the-1980s style graphics primitives.
