Scallops are edible bivalves similar to oysters and clams. They are found both in bay waters and in the sea. They do not attach themselves to a permanent anchorage, but move themselves through the water by opening and closing their shells. As a result, the muscle that controls the 'hinge' of the shell is much larger than that of oysters or clams.

The whole of the organism is edible, and in Europe, they are eaten in their entirety like oysters. In the US, however, only the shell muscle is eaten and it is this white cylinder of flesh that is commonly thought of in America as a scallop. The flavor is sweet and delicate, and is best served with a mild sauce of cream, cheese or butter that will not overpower the subtle flavor of the scallop itself.

Scallops are both fished and 'farmed' (that is, cultivated in water for harvest). Since they cannot survive out of water, they are shucked from their shells on board the fishing boat.

The bay scallop is much smaller than the sea scallop, and the edible muscle is less than an inch in diameter; usually a half-inch (about a centimeter) or smaller. The sea scallop's muscle can be as large as two inches (about 5 centimeters) in diameter. Sea scallops are sometimes cut into smaller shapes to pass as bay scallops. A 'faux scallop' made of shark is also available.

The scallop shell is the most familiar of shell-shapes; Shell Oil uses its distinctive fan-shape on all their service station signs. The shell is the symbol of the apostle James, and 'coquilles St. Jacques' means 'shells of St. James'. Crusaders of the Order of St. James wore a scallop shell as a sign of their allegiance.

The scallop shell is also associated historically with the cult of Venus. Botticelli's painting, the Birth of Venus (the famous 'Venus on the half-shell') shows the goddess apparently emerging from a scallop shell. She is actually arriving on land from her birth at sea on a scallop shell boat, driven to shore by the wind-gods Zephyr and Chloris.