The Web Map Service (WMS) is a standard defined by the Open Geospatial Consortium (OGC), which allows the publication of spatially referenced data maps dynamically based on geographic information. This international standard defines a "map" as a representation of geographic information in the form of a digital image file with PNG, GIF or JPEG extension, mainly. The WMS also supports the possibility of specifying whether the images sent have a certain transparency allowing the overlapping layers of different map servers.