What Unity Actually Is (Editor, Engine, Project)
See how the Editor, the runtime engine, and your project files divide responsibility before you write a line of code. Short card.
Three layers share the name “Unity,” and mixing them up is where a lot of beginner confusion starts: the Editor you click around in, the runtime engine that plays your built game, and the project folder that holds the assets and code both of them read.
Key points
The Editor is a tool, not the game
It never ships. It is where you arrange scenes, tune components, and preview play mode before building.
The engine is what actually runs
A build embeds a stripped-down runtime that loads your scenes and executes your scripts - no Editor UI included.
The project is the source of truth
Scenes, prefabs, scripts, and settings live as files on disk; the Editor and a build are two different ways of reading them.