1) The development of desert conditions as a result of human activity or climatic changes. 2) The process of land damage which allows the soil to spread like a desert in arid and semi-arid regions. There is a loss of vegetative cover and the soil deteriorates in texture, nutrient content and fertility. Desertification affects the lives of three-quarters of the world's population, 70% of all drylands and one quarter of the total land area of the planet. There are many reasons for desertification, but the majority are caused by human activities, overgrazing, deforestation, poor land management and over-exploitation. Agenda 21 states that the priority in combating desertification should be establishing preventive measures for lands that are not yet, or are only slightly, degraded. (Source: GEMET -LBC / WRIGHT) /n