A.C. Fabian discusses observational evidence of AGN feedback, where energy and radiation from the active nucleus of a massive galaxy interact with its interstellar medium, leading to gas ejection or heating. This process can stop star formation and accretion onto the black hole, explaining the proportionality between black hole mass and host galaxy mass. Direct evidence for radiative or quasar mode feedback is accumulating from exceptional objects, while kinetic or radio mode feedback, involving mechanical energy from jets, is common in massive elliptical galaxies. This mode is observed via X-ray bubbles in cool core clusters, heating the intracluster gas and reducing cooling. AGN feedback maintains a heating/cooling balance, with powerful jetted outbursts affecting galaxy cores. New telescopes will enhance observational data on all feedback modes. The radiative mode, or quasar/wind mode, operates when the AGN is luminous, pushing cold gas. The kinetic mode, or radio jet mode, involves jets in lower luminosity AGNs, heating gas in clusters. A third mode, associated with giant radio sources, may affect galaxy cores. AGN feedback is crucial for galaxy evolution, with the black hole mass correlated with stellar velocity dispersion. Observational evidence includes AGN-driven outflows in galaxies, such as in Mrk 231 and other ULIRGs, where gas is ejected at high velocities. AGN feedback is also seen in X-ray absorption features and radio jets, with some outflows exceeding starburst-driven ones. The kinetic mode is observed in cool core clusters, where jets heat gas, preventing cooling and star formation. Bubbles in these clusters, powered by AGN jets, are buoyant and rise in the intracluster medium. These bubbles, often seen in X-ray images, indicate AGN feedback. The energy from jets balances cooling, maintaining a heating/cooling equilibrium. Observations show that AGN feedback is essential for galaxy evolution, with the black hole mass linked to the host galaxy's stellar mass. The balance between heating and cooling is maintained through AGN feedback, with the kinetic mode playing a key role in preventing excessive cooling and star formation. Observational evidence from X-ray and radio studies supports the importance of AGN feedback in shaping galaxy evolution.A.C. Fabian discusses observational evidence of AGN feedback, where energy and radiation from the active nucleus of a massive galaxy interact with its interstellar medium, leading to gas ejection or heating. This process can stop star formation and accretion onto the black hole, explaining the proportionality between black hole mass and host galaxy mass. Direct evidence for radiative or quasar mode feedback is accumulating from exceptional objects, while kinetic or radio mode feedback, involving mechanical energy from jets, is common in massive elliptical galaxies. This mode is observed via X-ray bubbles in cool core clusters, heating the intracluster gas and reducing cooling. AGN feedback maintains a heating/cooling balance, with powerful jetted outbursts affecting galaxy cores. New telescopes will enhance observational data on all feedback modes. The radiative mode, or quasar/wind mode, operates when the AGN is luminous, pushing cold gas. The kinetic mode, or radio jet mode, involves jets in lower luminosity AGNs, heating gas in clusters. A third mode, associated with giant radio sources, may affect galaxy cores. AGN feedback is crucial for galaxy evolution, with the black hole mass correlated with stellar velocity dispersion. Observational evidence includes AGN-driven outflows in galaxies, such as in Mrk 231 and other ULIRGs, where gas is ejected at high velocities. AGN feedback is also seen in X-ray absorption features and radio jets, with some outflows exceeding starburst-driven ones. The kinetic mode is observed in cool core clusters, where jets heat gas, preventing cooling and star formation. Bubbles in these clusters, powered by AGN jets, are buoyant and rise in the intracluster medium. These bubbles, often seen in X-ray images, indicate AGN feedback. The energy from jets balances cooling, maintaining a heating/cooling equilibrium. Observations show that AGN feedback is essential for galaxy evolution, with the black hole mass linked to the host galaxy's stellar mass. The balance between heating and cooling is maintained through AGN feedback, with the kinetic mode playing a key role in preventing excessive cooling and star formation. Observational evidence from X-ray and radio studies supports the importance of AGN feedback in shaping galaxy evolution.