Web Map Service (WMS) was created by the
Open Geospatial Consortium (OGC) to “provide a simple
HTTP interface for requesting geo-registered map images from one or more
distributed geospatial databases.” To translate: WMS allows users to type a
special kind of URL, called a WMS request, into their browser. This request
gets sent to a WMS server, which is essentially a computer that stores a lot of
maps. The server sends a map back to the user, in the format specified by the
request.