Neutron reflectometry is a technique that evolved from X-ray reflectometry. While its theoretical underpinnings are largely the same, neutron reflectometry leverages the superior material penetration of neutrons and their unique sensitivity to light elements, which differs from X-rays. It’s an indispensable technique in soft matter science, particularly because deuterium substitution can create a large difference in scattering length density (SLD). Reflectometry is a powerful tool for obtaining information about the depth profile of thin films via a one-dimensional Fourier transform of the reflectivity. This makes it easier to understand than small-angle scattering, which requires a three-dimensional Fourier transform. Furthermore, the reflectivity equation can be derived more simply by expressing the SLD profile in differential form, making it easier to compare experimental data with theoretical models. This chapter will provide an overview of these features and key points of neutron reflectometry.