For many recipes, shrimp must be peeled before cooking. You may also devein them, which entails removing the black vein (the shrimp's digestive track) that runs down the back of the shrimp. (While most people find shrimp more appetizing if the vein is removed, this step is optional.) If you don't see the vein, it may be because your shrimp were farm-raised and "purged" before being sent to market, making the vein invisible and deveining unnecessary.

  To peel
  Gently press your thumbs on the inside curve of the shrimp to pry the shell loose.
  Peel away the shell, leaving the final tail segment intact for a small "handle" and a
  prettier presentation.

  To devein
  Using a paring knife, make a 1/4-inch-deep slit along the back, stopping just before
  the tail. Holding the shrimp under cool, running water, open the meat, exposing the
  vein. Carefully pull out the vein with a knife.