OpenGL

OpenGL, or Open Graphics Library, is a widely-used open standard and API for 2D and 3D rendering. It's a cross-platform API that can run on multiple operating systems, including Windows, macOS, and Linux.

It was first released in 1992 and offered an open alternative to Microsoft's proprietary solution, Direct3D, also known as DirectX, which was only available on Windows.

OpenGL is used in many applications, including video games, CAD software, and virtual reality applications. It is also used in scientific visualization and in the film and movie industry.

The evolution of OpenGL led to the creation of Vulkan, a cutting-edge rendering API. Vulkan is designed to be more flexible and powerful than OpenGL, especially with the most recent hardware. However, it is only supported by hardware released after 2012 and is more complex to use than OpenGL.

Godot 4 uses both Vulkan and OpenGL. The Forward+ and Mobile rendering engines use Vulkan. The Compatibility rendering engine uses OpenGL to offer compatibility with older hardware. You get to choose between these three rendering engines when creating a new Godot project.