Patch

Example of a patch model

A patch is a type of deformable object. A patch object is useful for creating gently curved surfaces, and provides very detailed control for manipulating complex geometry.

When you apply an Edit Patch modifier to an object or convert it to an editable patch object, the software converts the object's geometry into a collection of separate Bezier patches. Each patch is made up of three or four vertices connected by edges, defining a surface. Patches also have interior vertices that you can control, or let the software control for you.

You control a patch surface's shape by manipulating the vertices and edges. The surface is the renderable geometry of the object.