We now consider the environment of quasars in the widest possible sense, from the circumnuclear regions to very large scales of hundreds of kiloparsecs. The circumgalactic environment of nearby quasars has been widely studied since the late 1960s in an attempt to test its influence on the triggering of nuclear activity. The underlying hypothesis is that gravitational perturbations might ease the infall of matter toward the nucleus, providing accretion material for the central black hole.