Extrude
Pull new geometry out of a selection
Also known as: Blender extrude · Blender E key · Blender extrude faces · Blender inset · Extrude along normals
Definition
Extrude pulls new geometry out of selected vertices, edges or faces, creating connected faces that follow the selection. In Blender press E in Edit Mode and move the mouse, and use the axis keys to constrain the direction. Faces can be extruded along their normals with Alt+E, and Inset, on the I key, creates a smaller face inside a selected one. These two tools, with loop cuts, build most hard-surface and architectural shapes.
In production
Extrude with a clear plan for the topology: extruding faces creates new quads, while extruding edges that are not closed makes thin walls. Check for doubled or overlapping faces if you cancel an extrude by right-clicking, because that leaves the duplicate faces in place. Scale the extrusion by typing S and a value, and keep an eye on the normals.