Using Boolean modifiers to cut holes in objects

Booleans are a 3D extension of the Venn diagrams taught in algebra class. Named after George Boole, Boolean is pronounced Bool-ee-in with emphasis on Bool.

There are three kinds of Boolean operators, Difference, Intersection, and Union. The following figure shows what happens. The A circle represents the object to which you add the Boolean modifier. The B circle represents the object added by the Boolean modifier.

The Difference operation leaves all of the A object that is not part of the B object. With the Intersection operation, only what is common to both the A and B object is left. The Union operation combines the two objects.