Live2D

Live2D Cubism
Developer(s)	Live2D Inc.
Initial release	2010; 15 years ago
Platform	Windows, macOS
Website	https://www.live2d.com

Live2D Cubism, often referred to only as Live2D, is a suite of animation and art tools to facilitate the creation of rigged and layered 2D characters.

Functionality

Live2D is primarily used as a form of animation software to create characters for the purposes of animating them. Live2D uses a bone, mesh and layer technique to assemble components of a character, usually from a layered PSD file, to connect them and assign physics to given parts.

Once a Live2D model is created, it can be animated by assigning parameters to given bones and meshes and adjusted

Uses

Live2D is most commonly known for its use in creating Vtubers, Virtual Youtubers, as digital avatars for online performers and content creators. Live2D can also be used to create sprites for visual novels, similar to those are already commonly used within visual novels but with a significantly broader range of motion and variability than techniques without bone and mesh rigging.

Surrounding terminology

Model & Modelling

Modelling is the act of creating the art to be used in the creation of the Live2D model. This process usually involves creating layers to represent the various depths of which the Live2D model is displayable in respect to how the model is intended to move.

Rigging

Rigging is the act of assigning bones, meshes, and connecting them with the visuals of the model.

Motion Capture (Mo-cap)

Motion capture is the act of capturing movement and location data from a real life source, often through the means of cameras, software, and sometimes wearable capture hardware.

MO3

MO3 files, or Motion3 files, are files associated with the configuration of a Live2D model, and is used in the exporting of Live2D models from the Live2D model and rigging software into other systems, such as game software or motion capture software.

Cubism SDK

The Cubism SDK, also called the Live2D SDK, is a self-development kit intended to help game and other software developers integrate the Live2D technology into their applications. The SDK contains the full suite of Live2D features, and is readily available to be used in the following technologies:

Native (C & C++)
Java
Web
Unity Engine
Unreal Engine
Cocos Creator
MotionSync Plugin
Console platforms

The SDK has a variety of licensing requirements and options based on your use case. You can read more about that here.

Live2D Core

Live2D Core refers to the core library of Live2D, which implements basic features of MO3 model support, though notably does not support Cubism physics.