Focused ion beam (FIB) systems based on high-brightness gallium liquid-metal ion sources became commercially available in the late 1980s, although even today such instruments are relatively rare outside the somewhat enclosed world of semiconductor manufacturing. The use of FIB systems as precision sectioning tools down to a submicron scale and their ability to deposit metals and insulators on a micron scale is well documented. Recently, FIB systems have achieved spatial resolution rivaling that of the standard scanning electron microscope, giving them respectable capability as an imaging tool in addition to their sectioning and deposition capabilities. This improved resolution and novel FIB contrast mechanisms combined with the capability of FIB to produce in-situ stress-free bulk cross-sections and precision cross-sectional transmission electron microscopy specimens has recently attracted great interest among materials scientists. Examples of the use of FIB in materials science, both as a specimen preparation tool and as a microscope in its own right, are illustrated.