OGC WMTS

OGC WMTS (Web Map Tile Service) is the service enabling tiled vector and raster data for each scale interval to be saved as images in the server and users to view only the data of the place they view at the scale they view to be displayed.                       

You can find detailed information about global WMS services on the link below.

http://www.opengeospatial.org/standards/wmts