Head pins and eye pins are components used to make earrings.  Each is a component used to make a dangle. The head pin has a flat head on the top and the eye pin has a loop.

Each is available in a variety of wire gauges and lengths.  Typically the lengths will range from 1/2 inch up to 3 inches.

The metal type can also vary.  These may be found nickel plated, silver, plated, sterling silver, gold-plated, gold-filled, and solid gold

Creating with head pins and eye pins
1) In many cases when purchasing head pins, they may arrive a little bent out of shape but can be easily straightened.  A round nose pliers may be used to straighten it out.
2) Once straightened out, place a number of beads onto the pin.  You can use the same type or mix and match sizes, shapes and materials.
3) After placing the desired number of beads, cut the wire so that no more than 1/4 inch is left.
4) Using a round nose pliers, form a loop with the excess wire by rolling it away from you. The size of the loop will depend on how you position the end of the wire with the pliers.
5) Once the loop is formed, the dangle may now be attached to an ear wire.