"Curvature" in physics generally refers to the "intrinsic" curvature (see from within the space) as opposed to the extrinsic curvature (seen from a larger, embe

"Curvature" in physics generally refers to the "intrinsic" curvature (see from within the space) as opposed to the extrinsic curvature (seen from a larger, embedding space). A cylinder has zero intrinsic curvature, the same as a flat sheet of paper.