X-ray observations involve the use of X-ray telescopes and detectors to study celestial objects, such as stars, galaxies, black holes, and supernovae, in the X-ray part of the electromagnetic spectrum. X-rays are emitted by high-energy processes, such as hot gas accreting onto black holes or the remnants of dead stars. These observations provide valuable insight into the physical properties of these objects, such as temperature, density, and composition. X-ray observations are particularly useful for studying objects that are extremely hot, energetic, or compact, as these emit significant amounts of X-rays. Overall, X-ray observations are an important tool for astronomers to understand the universe and the processes that drive its evolution.