The fourth dimension (4D) is currently defined as a hypothetical construct since we live in the third dimension and must predict what the extra-spatial fourth dimension actually consists of. But generally, the 4D space is seen as an extension of the 3D space, providing further ways that objects can move.
Three Dimensions: The objects around you, the ones you can pick up, touch, and move around, are three-dimensional. These shapes have a third dimension: depth. Cubes, prisms, pyramids, spheres, cones, and cylinders are all examples of three-dimensional objects. Three-dimensional objects can be rotated in space.
