This elementary account of the differential geometry of curves and surfaces in space provides students with a good foundation for further study. It explores the ideas of curvature and torsion using the concept of the spin-vector, and it examines the curvature of surfaces, with particular reference to developable surfaces and ruled surfaces. The approach is by vector methods throughout, but only the most elementary vector algebra is assumed. The text consistently appeals first to geometrical intuition, and then the treatment is made fully rigorous as far as space permits. Many special types of surfaces occur among the examples, and a complete set of solutions provides readers with a full appreciation of all concepts.