not a sailor-question?
 

Could someone tell me what backstays are on a sailboat? If a picture is available that would be great.
thanks

Look at nearly any picture of a sailboat - the wire that extends from the top of the mast to the very back of the boat is the backstay. This can be one wire, two wires (double-backstay which brion hates for reasons described eslewhere), or one wire lead to a pair of wires like an inverted y (split backstay). Frequently backstays are more adjustable than other wires with either a hydraulic ram to pull the wire or a pulley (block and tackle) system set up to adjust the tension.