When your making jewelry for example earrings or necklaces you use jump rings to connect the pieces together
If you have an earring stud with a attached ring you can add a 2mm jump ring to a larger ring, bevel, pendant, charm, etc and attach it the two together. You can make it longer by attaching more jump rings.
Look at some dangle earrings here on Listia you can see how the jump rings attach things.