Backend

A backend is the part of a program or system that is not directly visible to the user. For example, in Godot, you create nodes in the editor to build your game. The engine takes those nodes, extracts their data, and turns it into an efficient structure that it can use to render the game.

That part that takes care of the data and the logic behind the scenes is called a backend. There are several of them. For example, for rendering, you can choose between several backends (rendering engines): Compatibility, Mobile, and Forward+. They offer different performance, compatibility, and quality trade-offs.

Similarly, you can use different physics engines with Godot: GodotPhysics, Jolt, Box2D... We call the different physics engines backends because you do not directly access the physics engines when coding Godot games. Instead, you interact with the Godot API, and Godot takes care of the rest. This API makes it possible to switch between backends without changing your code.