The Normalized Difference Vegetation Index (NDVI) is a numerical indicator used to assess vegetation health and density. It is calculated using satellite imagery, comparing the difference between near-infrared and red light reflected by plants. Healthy vegetation reflects more near-infrared light and absorbs more red light, resulting in higher NDVI values. NDVI values range from -1 to +1, where higher values indicate denser and healthier vegetation. This index is widely used in fields such as agriculture, forestry, and environmental monitoring to track changes in plant health over time and assess land cover changes across different regions.