Shrimp are small crustaceans that look somewhat like tiny, clawless lobsters. Only the tail is marketed and eaten, as a rule.
Shrimp come in many varieties, depending on where they are caught, but the particular variety is usually of little importance to the cook.
Shrimp are classified by count per pound—the higher the count, the smaller the shrimp. (For example, 16/20 means 16 to 20 per pound.) Classification systems differ by market—that is, in different markets a given size shrimp may have different names.
Large shrimp are more expensive per pound but require less work to peel and devein.
Yield: 1 lb raw shrimp (tails) in the shell yield about ½ lb peeled, cooked shrimp (500 g raw yields 250 g peeled, cooked).
The term prawn is sometimes used for large shrimp, sometimes for langoustines (see above). Use of the term varies from region to region.