Runtime

Runtime is when the game or a computer program is running. It spans all the time a game is visible on the screen and the player is playing it.

It contrasts with the notions of compile-time or build-time, which describe everything that occurs before the game runs, when working in the editor or upon launching the game. When you try running a scene in Godot, and the editor immediately opens the bottom panel and gives you an error, we say this is a compile-time error. This happens because the error occurred when the editor read and compiled your code.