Galactic nuclei refer to the central regions of galaxies, where there is a high concentration of stars, gas, and other material. These regions often contain supermassive black holes, which can influence the surrounding environment and play a key role in the evolution of galaxies. Galactic nuclei are studied using a variety of observational techniques, including radio, infrared, and X-ray observations, as well as theoretical models and simulations. Understanding the properties and dynamics of galactic nuclei is important for understanding the overall structure and evolution of galaxies.