Neutron and X-ray small-angle scattering provide, along with electron microscopy and diffraction, the principal techniques for the microscopic characterization of materials. Neutron, X-ray and electron beams each have quite different properties. In fact, each has unique advantages. The penetration of neutrons through most materials is responsible for many applications. The ever-increasing intensity of available X-ray beams is opening new fields. The advantage of electron beams is their ability to work in both real and reciprocal space. The problems of transforming the results of an experiment in reciprocal space to give an interpretation in real space are central to small-angle scattering, and are discussed. Several examples will be given of the successful use of small-angle neutron scattering applied to problems where other techniques have failed to make a decisive contribution.