The anus is the site where hemorrhoids occur, and the first place to talk about hemorrhoids is the anus. The anal canal, which is about 2.5 to 3.0 cm long, is formed when the fetus is 7 to 8 weeks old and slowly becomes a concave anal canal, while the large intestine also extends in the direction of the anus, as if it were a pipe. If the connection does not go smoothly, it is called “anus”, a disease in which there is no anus. The inner part of this line is the rectum, which is innervated by autonomic nerves and is not painful. The inner part of this line is the rectum, which is innervated by the autonomic nerves and is not painful. The exit (outer) side, which is the anal canal, is innervated by the somatic nerves and is very sensitive to pain. The anus is a very complex organ with very fine control and differentiation of stool, so it is prone to disease. And the symptoms vary depending on the site of occurrence. Even if a small hemorrhoid is produced, there can be very different symptoms, mainly bleeding or pain. Anal diseases, as the name implies, are diseases that occur in the anus, but because of the close correlation between the anus and rectum in terms of anatomy, physiology, symptoms and treatment, both doctors and patients consider them as a whole, which means that diseases that occur in the anus and rectum are called anal diseases. This is the scope of treatment of most hospitals’ anorectal department (or anorectal specialist, anorectal surgery, hemorrhoid and fistula department, hemorrhoid department), but of course, there are also a few hospitals that extend the scope of treatment of anorectal department to the whole colon due to departmental settings, that is, colon cancer, chronic colitis, constipation, colon polyps, ulcerative colitis, etc. are also included in the anorectal department. There are more than 70 kinds of diseases occurring in the anus and colon, and most of them occur in the anorectal segment, such as hemorrhoids, anal fissure, anal fistula, perianal abscess, anal papilloma, anal cryptitis, anal stenosis, anal incontinence, anal warts, anal eczema, anal pruritus, perianal neurodermatitis, anal contact dermatitis, anal ringworm, anal atresia, perianal dermatitis, anal canalitis, perineal descent syndrome, pelvic floor spasticity syndrome, puborectalis syndrome, sacrococcygeal teratoma, anal canal cancer, anal canal skin defect, rectal urethral fistula, pinworms, rectal cancer, rectal carcinoid, rectal polyps, prolapse, proctal protrusion, proctitis (ulcerative, radiation, gonorrhea, non-gonorrhea, non-specific, etc.), Crohn’s disease, rectovaginal fistula, rectal intussusception, fecal impaction, anorectal neurosis, isolated rectal Therefore, if patients have anal discomfort, it is advisable to find an anorectal specialist for examination and treatment, rather than just buy some medicine or go to the relevant departments such as general surgery, gastroenterology, so as not to delay the disease.