Geohashing is a technique that converts geographic coordinates (latitude and longitude) into a short string of letters and numbers. This string, the geohash, acts as a unique identifier representing a rectangular area on the Earth's surface. The system subdivides the world into a grid-like hierarchy, with each geohash defining one of the grid's cells. The longer the geohash string, the smaller and more precise the area it represents, allowing for location-based applications that need to track proximity or categorize items based on their geographic position.