Rigging is a nautical term for the system of ropes, wires and chains. They are used for attaching the sails to the mast and yardarms of the sailing vessel in order to catch the wind and increase sailing speed. One of the main differences between types of ship is in the way they are rigged. Most of pirate ships used these 2 types of rigging:
The square or rectangular sails that are hang symmetrically across the mast and supported by the horizontal spars (yardarms). They are quite strong and able to catch a more wind then other sails. They are mostly usable for sailing at the open sea.
The sails set behind the mast. They are not attached to the yardarms but are supported by the gaffs on top and the booms on bottom. Those sails are the best for sailing against the wind.