The EARTHTRACK app has been specifically designed to allow a wide range of users to collect ground truth data that then supports a) spatial retrieval and validation of attributes with pre-defined units (e.g., m, %) or categories (e.g., species type) from EO data (by allowing measurement and recording of these on the ground) and b) validation of derived land cover and change classifications obtained from satellite and airborne data. Earth Track points include near real time and historical records of observations of land cover and change on the ground that are geographically referenced (typically < 3-5 m positional accuracy) with well-defined categories that mirror those mapped at the national level through Living Wales (wales.livingearth.online). These points have been collected by the EarthTrack mobile application, which has been developed using Open Data Kit software and functionality but is being translated (in 2021/22) to a professional version available to be made available on the app stores and allowing use across major operating systems. All points are used to validate the land cover and land cover change maps from 2018 onwards and into the future, including in near real time. The Living Wales 10 m national land cover maps for Wales are constructed from environmental descriptors with predefined units (e.g., m, %) or codes (e.g., for lifeform or leaf type) retrieved or classified respectively primarily from satellite sensor data and according to the according to the United Nations (UN) Food and Agriculture Organisation (FAO) Land Cover Classification System (LCCS) Version 2 taxonomy (Di Gregorio, 2005). The EarthTrack mobile application exactly replicates how these land cover classes are constructed but at the ground level. The land cover change information also replicates that of the land cover maps for Wales, which is based on evidence, and uses the Global Change Taxonomy (with an associated glossary). This describes change across global environments according to at least 230 classes, with these defined according to the notation ‘impacts (pressures)’. These categories are derived from the Drivers-Pressures-States-Impacts-Response framework, where the states define the physical, chemical and/or biological characteristics of an environment. Impacts are discerned from state changes (either one or many) and result from pressures associated with abiotic or biotic events or processes (e.g., fires, droughts) or anthropogenic activities (e.g., ploughing, timber harvesting) with these driven primarily by climate/weather and economy. Di Gregorio, A.: Land Cover Classification System (LCCS). Classification concepts and user manual for software version 2. FAO Environment and Natural Resources Series, 8, 190 pp (2005).