AGNs are powered by the accretion of matter onto a supermassive black hole at the center of a galaxy.

Radio galaxies are AGNs that exhibit strong radio emission due to the presence of powerful jets of particles ejected from the central black hole.

The accretion disk is a region of hot, swirling gas that orbits the supermassive black hole and releases energy through friction and gravitational forces.

Quasars are extremely luminous AGNs that are powered by the accretion of matter onto a supermassive black hole.

Relativistic jets are collimated beams of high-energy particles ejected from the central black hole in AGNs.

Blazars are a type of AGN that exhibits rapid variability in its brightness and strong emission of gamma rays due to the orientation of its relativistic jets toward Earth.

The broad-line region is a region of ionized gas close to the supermassive black hole that emits strong emission lines due to the high velocities of the gas.

LINERs (Low-Ionization Nuclear Emission-line Regions) are AGNs with relatively low luminosity and weak emission lines.

Accretion is the process by which matter falls onto the supermassive black hole in an AGN, releasing energy and powering the AGN's activity.

X-ray galaxies are AGNs that exhibit strong emission of X-rays due to the high temperatures and energetic processes occurring near the supermassive black hole.

The narrow-line region is a region of less ionized gas farther from the supermassive black hole that emits weaker emission lines due to the lower velocities of the gas.

Infrared galaxies are AGNs that exhibit strong emission of infrared radiation due to the presence of dust and molecular gas in the central regions of the galaxy.

Doppler beaming is the phenomenon where the emission from an AGN appears to be brighter in one direction due to the relativistic motion of the emitting material toward or away from the observer.

UV galaxies are AGNs that exhibit strong emission of ultraviolet radiation due to the high temperatures and energetic processes occurring near the supermassive black hole.

The event horizon is the boundary around the supermassive black hole in an AGN beyond which nothing, not even light, can escape.