A web map service (WMS) is a OGC standard for sharing georeferenced data through the web from a geospatial database. A request is made through a HTTP client which calls several parameters such as a layer name, the coordinates for an area of interest, the image format, the coordinate system of the data that will be viewed in the web browser, and any defined styles associated with the data.
The WMS standard has been criticized in the past as slow and cumbersome, but its use has become more widespread as many online mapping clients have incorporated its use. Google and Bing both allow for WMS layers to be read into their online mapping tools, and many software providers now have WMS servers built into their platforms from ArcGIS Server, GeoServer to FortiusOne. I enjoy using WMS data because it enables access to large and complicated datasets by users who may not be geospatial professionals through easy to use web interfaces. And, it really supports my mantra of single dataset, many uses…
There are a number of excellent resources that explain WMS in detail, in fact, much better than I can. Here are a few good links to help you get started:
- MassGIS – Great demonstration of WMS capabilities
- WMS explanation from Wikipedia (yes, I referenced Wikipedia, I am ashamed too)
- OGC WMS standards
- Adding WMS data in Google Earth
- Example of WMS in MapServer