Unity provides three UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary systems that you can use to create user interfaces (UI) for the Unity Editor and applications made in the Unity Editor:
This page provides an overview of each.
UI Toolkit is the newest UI system in Unity. It’s designed to optimize performance across platforms, and is based on standard web technologies. You can use UI Toolkit to create extensions for the Unity Editor, and to create runtime UI for games and applications.
UI Toolkit includes:
Unity intends for UI Toolkit to become the recommended UI system for new UI development projects, but it is still missing some features found in Unity UI (uGUI) and IMGUI.
The Unity User Interface (Unity UI) package (also called uGUI) is an older, GameObject-based UI system that you can use to develop runtime UI for games and applications. In Unity UI, you use components and the Game view to arrange, position, and style the user interface. It supports advanced rendering and text features.
Immediate Mode Graphical User Interface (IMGUI) is a code-driven UI Toolkit that uses the
OnGUI function, and scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary that implement it, to draw and manage user interfaces. You can use IMGUI to create custom InspectorsA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
See in Glossary for script components, extensions for the Unity Editor, and in-game debugging displays. It is not recommended for building runtime UI.
Unity intends for UI Toolkit to become the recommended UI system for new UI development projects, but it is still missing some features found in Unity UI (uGUI) and IMGUI. These older systems are better in certain use cases, and are required to support legacy projects.
Your choice of UI system for a given project depends on the kind of UI you plan to develop, and the features you need support for.
For a comparison of the available UI systems, see the Comparison of UI systems in Unity.