Web GIS has been defined in the ArcGIS Help 10.1 as:
Web GIS is a type of distributed information system, comprising at least a server and a client, where the server is a GIS server and the client is a web browser, desktop application, or mobile application. In its simplest form, web GIS can be defined as any GIS that uses web technology to communicate between a server and a client.
It is like Web Mapping but has been extended by the inclusion of geoprocessing capabilities such as Web Processing Services (WPS), ArcGIS Geoprocessing Services, etc.
Normally you will be using a specific web GIS product such as:
- ArcGIS for Server
- ERDAS APOLLO
- FME Server
and if that is the case then this
web-gis tag is superfluous and should NOT be used.
However, if you are using multiple web GIS products (i.e. using up too many of your 5 tags) or have a question about that part of a spatial architecture in more conceptual terms then it can be considered available as a "tag of last resort".