Marching Cubes is an algorithm used in computer graphics to extract a polygonal mesh from a three-dimensional scalar field. It works by dividing the 3D space into a grid of cubes and determining how the surface intersects each cube based on the scalar values at its corners. The algorithm generates triangles to represent the surface within each cube, allowing for a smooth representation of complex shapes. Marching Cubes is widely used in various fields, including medical imaging, where it helps visualize structures like organs from CT or MRI scans.