This lecture covers the historical perspective and introduction to X-rays, their properties, and applications in physics, chemistry, biology, and medicine. It delves into X-ray diffraction of crystals, the power of X-rays in scattering with atomic resolution, and the specific colors of elements in the X-ray spectral regime. The lecture also discusses the importance of X-ray interactions with matter, the Debye-Waller factor, and the Debye-Scherrer formula. Furthermore, it explores the science opportunities offered by X-rays, including dynamics and structure analysis, charge and energy transfer, quantum control, and non-linear photon-matter interactions.