External hemorrhoids refer to hemorrhoids below the dentate line and are divided into four types. The first type is the connective tissue type of external hemorrhoids, which are formed by the proliferation and bulging of excess skin at the anal margin. The second type is the varicose vein type of external hemorrhoids, formed by the dilation and bending of the venous plexus below the dentate line. The third type is inflammatory external hemorrhoids, which is a state where external hemorrhoids become inflamed. The fourth type is the thrombosed external hemorrhoid, which is formed by bleeding due to the rupture of the subcutaneous veins at the anal margin, resulting in a blood clot.