The introduction of pulse width modulated LED lighting in automotive applications has created the phenomenon of LED flicker. In essence, LED flicker is an imaging artifact, whereby a light source will appear to flicker when image by a camera system, even though the light will appear constant to a human observer. The implications of LED flicker vary, depending on the imaging application. In some cases, it can simply degrade image quality by causing annoying flicker to a human observer. However, LED flicker has the potential to significantly impact the performance of critical autonomous driving functions. In this paper, the root cause of LED flicker is reviewed, and its impact on automotive use cases is explored. Guidelines on measurement and assessment of LED flicker are also provided.