Later on, Google Maps arrived, providing an easy to use map integration to regular web sites, even without having to manage mapping data. Thus, Google Maps specific code was added to Tiki, which was convenient for a lot of people.
Then, after a community discussion, starting in Tiki7, OpenLayers (another option was Mapstraction) was added as a native way to handle maps, which permits the use of tiles from Google Maps, Bing Maps, OpenStreetMap (which is like Wikipedia but for maps), MapQuest (which serves OpenStreetMap maps), etc.
In Tiki12, all Google Maps specific code was removed in favor of using OpenLayers, so Google Maps is accessible via the OpenLayers Google Layer. In addition the Natural Access project added further new capabilities to upload any existing line and polygon data as files and to be able to further customise how data objects were shown on the underlying map layer.
It should be noted that from Tiki15 all MapServer-specific code has been removed. Also OpenLayers 2.x continues to be used for the map layer and integration with Tiki to allow editable map objects to be overlaid on the map layer but experimentation has started with the integration of OpenLayers 3..x.
Map-related documentation currently (as of February 2016) still makes reference to the different historical approaches but as it continues to be improved the older methods that are no longer used will be deprecated/removed. Volunteers to help with documentation improvement : please contact marclaporte at tiki dot org
"OpenStreetMap is a free editable map of the whole world. It is made by people like you. OpenStreetMap allows you to view, edit and use geographical data in a collaborative way from anywhere on Earth." Source: http://www.openstreetmap.org/.
Please listen to an interview with OpenStreetMap founder.