A reciprocal lattice is a mathematical construct used in solid-state physics and crystallography to describe the periodicity of a crystal in momentum space. It is formed from the Fourier transform of the crystal's real-space lattice, allowing for the analysis of wave vectors associated with the crystal's electronic and vibrational properties. In a reciprocal lattice, each point corresponds to a set of planes in the real lattice, defined by the Bravais lattice vectors. This concept is essential for understanding phenomena such as X-ray diffraction and the behavior of electrons in band theory, as it helps visualize how waves interact with the crystal structure.