What are the 3 main types of sculpture?

What are the 3 main types of sculpture?
The three main types of sculpture are assemblage, in the round, and relief. In the round is what we usually think of when we think of sculptures; free standing solid piece surrounded on all four sides by empty space. Assemblage is a sculpture, free standing like in the round, but made of different objects put together. Lastly, a relief sculpture is a form or picture that projects out from or is mounted on a vertical surface.