End milling is a machining process used to create complex shapes and features on a workpiece. It involves a rotating cutting tool, known as an end mill, which has multiple cutting edges. The tool moves vertically and horizontally to remove material, allowing for precise cuts and finishes. This technique is commonly used in CNC (Computer Numerical Control) machining, where the movement of the end mill is controlled by a computer program. End milling can produce various geometries, including slots, pockets, and contours, making it essential in industries like manufacturing and aerospace.