Scripting
Also said as Scripting language, Gameplay scripting, Lua
Writing game behaviour in a simpler language that the engine reads and runs, while the fast, difficult parts stay in the engine.
Designers can change a boss without rebuilding the game or breaking the renderer, and a mistake costs an error message instead of a crash. It also runs slower, so heavy loops stay in the engine.
Say it
“Keep pathfinding in the engine, and put every boss's phases in a Lua script, so a designer can change the timings and try them without a programmer.”
Where you’ve seen it
World of Warcraft runs its interface add-ons in Lua, which is why players can replace most of its interface with add-ons they write themselves.
Not to be confused with visual scripting
Scripting is usually typed text. Visual scripting, such as Unreal's Blueprints, is the same idea drawn as boxes and wires.