This talk provided a brief overview of the Geo-Wiki application (https://www.geo-wiki.org) for the collection of land cover and land use reference data using crowdsourcing and the visual interpretation of very high-resolution satellite imagery. These reference data have been used to create training data sets and to validate land cover/land use products in a range of different applications including cropland extent, forest management and the drivers of deforestation, which will be presented in brief.