X.Org is an implementation of the X Window System Core Protocol it was forked off from XFree86 around 2003 Subpages X.Org Server is the free and open-source implementation of the display server for the X Protocol stewarded by the X.Org Foundation Link to original Xcb is a low-level C wrapper around the X protocol (client-side) Link to original Xlib is a high-level C wrapper around the X protocol (client-side) Link to original