This course introduces the principles of using Earth Observation (EO) for forest monitoring, covering key remote sensing techniques, data sources, and analytical methods. Participants will learn how Copernicus datasets, vegetation indices, and classification techniques are applied to assess forest cover, detect changes, and support sustainable management. As the first part of the Forest Monitoring Training Series, this session provides the foundational knowledge needed for practical (Part II - April/May 2025; onsite)  and application (Part III - July 2025; online) trainings.