Corbels were necessary in earlier times. They were a good source of support. They would support structures such as beams and arches.
Corbels were first built by the French, but the word corbel came from a Latin word. The Latin word is corbellus. Corbellus means a beak-like appearance.
Most of the earlier corbels were made of stone. The stone corbels would usually look like granite. There are some that were made of wood. They were good for decoration on window sills, along the side of building, or around the doors. They could be plain, but most of them had images carved into them. The images range from unique designs to humans to animals. You have an endless choice of images to have carved in the corbel.
On many older buildings in France and other places, corbels will be lining the way a few feet below the roof. The corbels would have a table on top of them. This table is what housed the gutter. It put a little more decoration in the building.
In medieval times, corbels were used for the arches. They helped support the upper stories. There was also spaces between the corbels. The areas were used to drop objects on attackers. As years passed, the corbels were for decoration purposes only.