Toolhead Terminology

The terms toolhead, extruder, hotend, and nozzle are often thrown around and are misused. To level set, this document describes the various parts that make up a toolhead:

Extruder. The component that moves the filament.

Hotend. The component that heats the plastic into a molten state.

Nozzle. The component that distributes the plastic (and is part of the overall hotend assembly).

Toolhead. The toolhead (or sometimes called the printhead) is comprised of each of these parts.
(if the extruder is a direct drive extruder... Bowden extruders are typically attached to the frame and not part of the toolhead)


Here are some inconsistencies found in OctoPrint:

The Navbar calls it Tool:



...as does the Dashboard plugin:



The Temperature tab page calls it Hotend:



...and in the Temperature Settings page, it's called Extruder:

(note: just to clarify, you can't set the temperature of an extruder)



Even OctoPrint's SDK intermingles the terminology:


So, just to level set, in OctoScreen, when you set the temperature, you are controlling the hotend. When you extrude or retract plastic, you are controlling the extruder. And when you move the assembly, you are moving the toolhead.