When we move from 2D Shapes to 3D shapes we "extrude a profile". This means that we take a 2D image and pull it into a 3D volumetric shape. A real world example of an extrusion machine are Playdough sets we grew up with where the clay was pushed though a hole to extrude a particular shape. This most often was extruding a cylinder from a circular hole.
Another type of extrusion is the revolve. Think about the cross-section of a bicycle tire which is mostly circular, but it is extruded in a torus (donut) shape around an axis (axle). The image below shows the transition in 1st grade yesterday from hand drawn 2D profiles to 3D revolutions of those shapes.