What is "mapathon"

A Mapathon is a coordinated mapping event. It is often held inside (armchair mapping) but can also be an outside or combined activity.

They can be organized

• from Google for massive updating Google map: see https://en.wikipedia.org/w/index.php?title=Google_Mapathon
• from caritative organizations for multiple [NGO] shared under OpenStreetMap: see http://www.missingmaps.org/