According to its web site, “The Khronos Group is a not-for-profit industry consortium creating open standards for the authoring and acceleration of parallel computing, graphics, dynamic media, computer vision, and sensor processing on a wide variety of platforms and devices.”
Role of Khronos
The Khronos Group is concerned with devising and setting standards for graphics and video processing, among other things. The standards it is involved in include the following:
OpenGL
OpenGL ES
OpenMAX
EGL
OpenVG
OpenCL
What relevance does this have to the RPi? Well, the RPi supports OpenGL ES, OpenVG, ...