A mapping party is an opportunity for everyone to learn about OpenStreetMap, why it is important, some simple ways of using it, and how to help improve OpenStreetMap data for the benefit of all.
It's also an opportunity for experienced OSM contributors to learn new apps, workflows, and how to contribute to related projects like Panoramax, Mangrove Reviews, and Wikimedia Commons.
After an initial 30-minute orientation, all contributors (new and old) are divided into teams, and work together to improve the map of the surrounding area on OSM.