Mesh Decimation is a process used in computer graphics to reduce the number of polygons in a 3D model while preserving its overall shape and appearance. This technique is essential for optimizing models for real-time applications, such as video games and virtual reality, where performance is crucial. By simplifying the mesh, Mesh Decimation helps decrease rendering times and improve performance without significantly sacrificing visual quality. It works by removing unnecessary vertices and edges, allowing for faster processing and easier manipulation of 3D objects in various software applications.