What does keys mean in Florida keys?

Keys in the Florida Keys refers to the islands that make up the Florida Keys archipelago. The keys are a chain of islands stretching from the southern tip of the Florida peninsula to the Dry Tortugas, a group of islands about 70 miles (110 km) west of Key West. The keys are made up of coral reefs that were formed over millions of years by the accumulation of the skeletons of tiny marine organisms. The islands are known for their beautiful beaches, clear waters, and abundant marine life.