The facial triangle, also known as the T-zone, is a long line formed by the forehead and the brow bone on both sides of the face, plus the bridge of the nose, forming a downward area with an inverted triangle shape. This area has a large number of sebaceous glands and sweat glands, so it is prone to oil production, resulting in seborrhea, including seborrhea or acne. This triangle is again different from the danger triangle of the face. For the danger triangle, it mainly refers to the area from the root of the nose to the two sides of the corners of the mouth, forming a positive triangle shape, and is also called the danger triangle because after inflammation occurs, if squeezed, it can cause local infection to expand and even form intracranial infection.