Crab bisque is a rich, pureed soup made by simmering crab shells, meat, and aromatics in stock, then straining the liquid to a smooth, velvety consistency and enriching it with cream. That straining step is what separates a bisque from a chowder or crab soup, both of which keep chunks of meat and vegetable in the finished dish.
Cream, sherry, and seasonings such as thyme, bay leaf, and white pepper are typically added to round out the crab flavor. Blue crab, Dungeness crab, or lump crab meat can all be used, and some recipes fold in shrimp or lobster for added depth. It's popular in coastal cooking wherever crab is plentiful, including the Chesapeake Bay area and the Gulf Coast, where cooks often season it with Old Bay or use a tomato-based stock.
Crab bisque is usually served as a first course or light main, often with crusty bread, and it can also serve as a base for other crab preparations such as crab cakes or a seafood stew.