Running Rigging Glossary

Sailboat Rigging can be divided in to 2 categories:

Standing Rigging - the wires and ropes that hold up the mast, also known as shrouds or stays

Running Rigging - the ropes (and wires) that control the sails on a yacht
There are a large number of different terms that cover the use for which each rope is employed.

The most common generic terms are sheets and halyards.

Sheets - normally attached to the clew of the sail and control the shape and angle to the wind - each individual sheet is identified by the name of the sail as a prefix e.g. Jib sheets, genoa sheets, yankee sheets, staysail sheets, code zero sheets, gennaker sheets, cruising chute sheets, mainsheets, mizzen sheets - where these are a pair, they may also be classified as port or starboard. Spinnaker Sheets are used in conjunction with Spinnaker Guys and a spinnaker pole to control the shape of the spinnaker on either gybe

Halyards - attached to the head of a sail and used to haul a sail up the mast - in the same way as sheets, each halyard is identified by the name of the sail as a prefix e.g. main halyard.

Sheets and halyards are part of a more generic category: Control Lines or a little more obscurely, Preventers
Control Lines include sheets and halyards and all the other ropes and wires that contribute to the efficient mangement of a yacht's sail area.
A rope that stops an accidental gybe is commonly referred to as a preventer.
However, most of the ropes that comprise a yacht's running rigging can be described as preventers i.e. a rope that is preventing something or control lines i.e. a rope that is controlling something

Control Lines:

Tack Line 
- attached to the tack of a sail to make the length of the luff adjustable - common on loose footed reaching/running headsails e.g. gennakers but also used on more traditional rigs e.g. dipping lugsails

In Hauler or Tweaker - attached to a headsail (jib/genoa/yankee/code zero) sheet and used to bring the angle of the lead nearer to the centreline than the normal setting.

Barber Hauler - attached to a headsail sheet and used to create more downward pressure and generally from a point further outboard than the normal fairlead setting

Downhaul or Cunningham - attached to the tack of a mainsail and used to create tension in the luff.

Kicker or Vang - diagonal line or purchase system (block and tackle) from base of mast to a point on the underside of the boom - used to create downward tension on the boom and subsequently the leach of the sail

Outhaul - generally attached to the clew of a mainsail to adjust the foot tension

Reefing Line or Reefing Pennant - Lines reeved through the boom and the mainsail to facilitate a reduction in mainsail area

Lazyjack Line - used for guiding and controlling the mainsail as it is dropped

Running Backstays or Checkstays - adjustable version of the backstay, generally consisting of a very low stretch standing part (single line) attached to a purchase system for adjusting the tension

Preventer - line deployed to prevent the mainsail boom from accidentally gybing or control the speed of the boom's transition during a gybe