The dart covers three broad categories of ranged weapons:
The second is a weapon more like a lawn-dart with large flights and (normally) a weighted head such as the plumbata used by some late Roman legionnaries. These were almost always thrown by hand, although there is historical evidence of them being sling-thrown as well.
Finally there are the even smaller darts used as ammunition for a blowpipe - normally no more than a sliver of wood or metal with some kind of flights and relying on a payload of drugs or poison for its effect.
It should be noted that there is little or no historical evidence for anything resembling the modern pub-dart ever being used as a weapon - their appearance in assorted fRPGs is likely to be based on misunderstanding of the size of actual historical weapons like the plumbata. If they must be included, they would be best filed alongside the blowpipe darts as a delivery system rather than a pure weapon.
Game and Story Use
- Bizarrely these used to be one of the permitted weapons for a magic user in old school D&D, possibly brought on by visions of weaponised pub-darts. These is probably still viable if the GM is prepared to abandon the silly ideas about the morality of using poison inherent in the same system.
- Blowpipe darts are probably something of a signature weapon for whoever wears the jungle-dweller "hat" in your campaign - there are at least three blowpipe using regions in the real world, all of which are jungled to some degree and seem to be culturally independant of one another.
- Apart from that, the dart tends to fill the same historical niches as the javelin.