The Full Form of WCS is World Coordinate System.

An elaborate set of FITS conventions has been defined to specify the physical, or world, coordinates to be attached to each pixel of an N-dimensional image. By world coordinates, one means coordinates that serve to locate a measurement in some multi-dimensional parameter space. A common example is to specify the Right Ascension and Declination on the sky associated with a given the pixel location in a celestial image. An archive of discussions about WCS issues that have taken place on the [email protected] email exploder is available on the NRAO web site.

The WCS conventions are defined in a set of formal papers, 4 of which have been officially approved as part of the FITS standard by the IAU-FWG. Much of the content of the first 3 papers has been directly incorporated into Version 3 of the FITS Standard document and the 4th paper on Time coordinates has been incorporated into Version 4.