A runabout is a versatile space-faring, warp-capable vessel larger than a shuttlecraft and smaller than a starship. Like shuttlecraft, runabouts can sometimes be assigned to starships or space stations as secondary craft. Unlike shuttlecraft, runabouts usually have their own unique registry.
While shuttlecraft are normally for short-distance trips, runabouts can sustain a small crew for longer periods of time as they usually contain separate living areas and more crew amenities for the crew members. Runabouts also have a wider range of weaponry and more complex drive systems than some shuttlecraft.
Starfleet used several types of runabouts throughout its history, including the Danube class. (DS9: "Emissary", et al) The Danube class consisted of a modular design and was originally capable of warp 5. (DS9: "Dax")