Maps have been supported in Tiki since 2003 (which is why some call it a GeoCMS). There is geo-related info in various places (users, trackers, image galleries, articles, blog posts, etc.). This was originally done using MapServer, an active and powerful FLOSS mapping solution. However, it requires a dedicated server and more importantly, access to map data (which is not easy).
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.
In 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.
In Tiki20 integration with OpenLayers 3.x and higher was improved, and more features were exposed through the corresponding PluginMap parameters, as well as adding new tilesets, some of them using vector tiles instead of just the usual raster tiles.
Map-related documentation, as of summer of 2019, 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