  Selected topics on precision tests of the Standard Model of the Electroweak
and the Strong Interaction at the LEP $e^+e^-$ collider are presented,
including an update of the world summary of measurements of $\alpha_s$,
representing the state of knowledge of summer 1999. This write-up of lecture
notes consists of a reproduction of slides, pictures and tables, supplemented
by a short descriptive text and a list of relevant references.
