A thorough understanding of facial anatomical structures is essential for the safe and effective application of injectables in facial aesthetic procedures. By familiarizing oneself with the anatomical distribution of the face’s major blood vessels (arteries and veins), nerves, muscles, fat layers, and retaining ligaments, complications such as vascular occlusion and nerve injury from intravascular injection can be prevented, and optimal aesthetic outcomes can be achieved. In particular, since fillers are used to restore volume and improve contours, it is important to inject them into safe layers considering the neural and vascular structures. This chapter systematically organizes the essential anatomical concepts required for filler and other injectable procedures, aiming to provide evidence-based knowledge for more precise and safer treatments.