The document defines agroforestry and provides a classification system for agroforestry systems. It states that agroforestry is the intentional planting or retention of trees on farms through spatial and temporal arrangements. It then describes four ways to classify agroforestry systems: 1) based on vegetation structure, 2) based on function, 3) based on socio-economic activities, and 4) based on ecological conditions. The classification system aims to categorize different agroforestry systems based on their components, functions, and suitability for various environmental and socioeconomic contexts.