WMS
OpenGIS® Web Map Service Interface Standard (WMS) provides a simple HTTP interface for requesting geo-registered map images from one or more distributed geospatial databases.
WFS
OpenGIS® Web Features Service Interface Standard (WFS) provides an interface allowing requests for geographical features across the web using platform-independent calls.
REST
REST API Map Service resource provides basic information about the map, including the layers, spatial reference, initial and full extents, map units, metadata, and copyright text.