From the central kiloparsec to the central parsec

In this review I address some of the global properties of galaxies which show nuclear activity, or central starbursts. Confining my attention to the inner kiloparsec, I discuss properties of bulges, with a brief look at central black holes, and then go on to talk about bars, single and multiple, and other circumnuclear structures: discs, rings and spirals. Recent work is reviewed, addressed to whether the presence of bars favors that of AGN, followed by a specific diagnostic look at the distinction between AGN and starbursts. I suggest that the reason why there is little clear-cut distinction between host galaxies (even their central kiloparsec), with central activity and galaxies without activity is the cyclical nature of this activity: the same galaxy may be active, or have a starburst, or show neither of these phenomena, depending on when it is observed. The inflow leading to an accumulation of mass to the center of a barred galaxy tends to disrupt the bar, and massive starbursts are self-limiting due to their huge energy outflow which disrupts their placental clouds. These attempts by galaxies to destroy evidence make the interplay of observation and theory more challenging. The remaining papers in these proceedings will show how astronomers are responding to the challenge.