Expressions
Expressions are a feature of VRChat avatars. They allow you to run various actions or toggles on your avatar. They can be used mainly through the Action Menu, or the Expressions wing on the Quick Menu or Main Menu.
Expressions are user-customized menus and actions meant to allow flexibility and easy access to avatar features. You can find more information at 
Avatar Creators Docs.
The in-game Expressions menu is accessible through the Action Menu, or the Expressions wing on the Quick Menu or Main Menu on any version of VRChat. This information is transferred globally to others users, so information is synchronized.
Expressions in the SDK
Expressions are edited, using parameters in the VRChat SDK.
Base expressions
When no expressions are configured, a default expression menu with base animations is added to the avatar, which contain the following animations:
- Wave
- Clap
- Point
- Cheer
- Dance
- Backflip
- Die
- Sadness
Custom expressions
To add custom expressions, you need to create an Expression Menu file and an Expression Parameter file, then add them to the VRChat Avatar Descriptor. The menu will allow you to create the parameter entries, that will compile on the Expression menus for your avatar. The parameters are the variables that are controlled by the menu. You will also define technical information about those variables, like if they need to be synchronized for other users.
Controls
You can create a maximum of 8 controls per page. When creating a control, you choose the type of the control. These control types include:
- Button
- Toggle
- Sub Menu
- Two Axis Puppet
- Four Axis Puppet
- Radial Puppet
Puppet Menu Example
As you move your joystick/touchpad/mouse in various directions, you drive animation parameters to different values. This setup allows blending between various "moods," such as "happy" and "surprised," or other adjacent moods.
Anything that is set as a parameter can be controlled from this menu. There are also toggle buttons and other types of UI elements still in development.
You can pull up one menu on either hand (or both simultaneously). By default, you "flick" to select an option. In the Action Menu settings, you can choose to use the Trigger to select an option. To back out after making a selection in the Expressions menu, pull the trigger.
Official resources
- Avatar 3.0 Hub world on VRChat
- Expression Menu and Controls on Creator Docs
- Playable Layers on Creator Docs
