ExpressKeys

Overview

ExpresKeys is a Wacom-specific term, but people use it in general additional inputs for any tablet. Drawing tablets often have additional "inputs" such as:

Buttons (both physical and capacitive)
Dials
Touch-sensitive strips

Other names

Huion calls these buttons "Press Keys"

Disabling Express Keys

Some people love using these kind of inputs, but some people do not like them because either they

take up space on the tablet
are accidentally triggered
or their workflow just doesn't benefit from them

For these cases, you should be aware that these inputs can often be configured in the tablet driver to "do nothing".

Actions

You can map the buttons to take a variety of actions. Broadly the categories are

Mouse-related actions - right click, left-click, double click
System navigation - scroll left, scroll right, zoom in/out, pan, switch applications
System tasks - run application, open a file
Keyboard - Press a key, hold down a modifier key

Global vs application configuration

Tablet drivers also let you configure how these buttons work depending on the app you are using.

For example you can set a button to

Increase brush size when you are using Photoshop
Increase opacity when you are using Clip Studio Paint
Increase the volume of your speakers under all other conditions

Common useful assignments

Buttons

Undo | Redo
Zoom In | Out | to 100% | Zoom to Fit
Increase | Decrease brush size
Increase | Decrease burhs opacity
Rotate Left | Right | Reset to 0 degrees
Switch between tools (brush, eyedropper, etc.)
Select All | None | Invert | Lasso selection | color similarity selection
Go to layer above | below
Display toggle
Precision mode
Pan/Scroll

Rotary dials

These are great for "paired" tasks

Zoom In / Out
Increase / Decrease brush size
Increase / Decrease brush opacity
Rotate canvas

Some rotary dials support turning as well as a third press action. This is useful for a situations where there are three related actions such as rotate right, ritate left, and reset rotation.