  Analogue spacetimes, (and more boldly, analogue models both of and for
gravity), have attracted significant and increasing attention over the last
decade and a half. Perhaps the most straightforward physical example, which
serves as a template for most of the others, is Bill Unruh's model for a dumb
hole, (mute black hole, acoustic black hole), wherein sound is dragged along by
a moving fluid --- and can even be trapped behind an acoustic horizon. This and
related analogue models for curved spacetimes are useful in many ways: Analogue
spacetimes provide general relativists with extremely concrete physical models
to help focus their thinking, and conversely the techniques of curved spacetime
can sometimes help improve our understanding of condensed matter and/or optical
systems by providing an unexpected and countervailing viewpoint. In this
introductory chapter, I shall provide a few simple examples of analogue
spacetimes as general background for the rest of the contributions.
