If you use a family tree program that stores coordinates at places, then these coordinates are used by Genealogy Online!
If no coordinates are available in the GEDCOM file supplied, they will be looked up in the Geonames.org geographic database. This method can be inaccurate. An example: a person is born in Noordwijk. However, there are 3 places in the coordinate file that are called Noordwijk (in the provinces of Groningen, Drenthe and South Holland respectively). The first Noordwijk will then be selected (possibly incorrectly). As an author you can increase accuracy by:
The author receives feedback or place names from the administration page that are not or not clearly identified.