question about source code folder(engine/source/programs)

in unreal engine source code and under folder in the source folder under engine

what does this mean"Programs - External tools used by the engine or editor."

does external tools mean tools that run in background of the engine(i.e running but not visible when using the engine and runs in background and used by engine and editor

or does it run and actually physically there i.e using it engine when the engine is being used to create games