What is anal disease? The answer is easy, but not always comprehensive. In general, anorectal disease is the term for all inflammatory diseases, tumors, trauma and other diseases of the large intestine below the cecum. In other words, anorectal surgery covers the diagnosis and treatment of all benign and malignant diseases of the colon, rectum and anus. 1.Common colon diseases: colitis (such as ulcerative colitis, Crohn’s disease, etc.), colon polyps (single or multiple polyps, familial polyposis, etc.), colon tumors (colon cancer, gastrointestinal mesenchymal tumors and other tumors) and functional diseases (constipation, irritable bowel syndrome, etc.). 2.Common rectal diseases: proctitis (ulcerative, bacterial), rectal polyps, rectal prolapse, rectal cancer, etc. 3.Anal canal and anal diseases: anal canalitis, anal sinusitis, anal papilloma, hemorrhoids, anal fistula, abscess, tumor and congenital anal diseases, etc. 4.Other: outlet obstructive constipation, anal venereal disease, anal neurosis, complications caused by surgery and trauma, etc.