The anus is the most end of the anus and belongs to the department of anorectal surgery. The three main roles of the anus are to expel the waste gas present in the human body, excrete feces, control the involuntary overflow of fecal mucus through the sphincter, and prevent external liquids and gases from entering the anal canal and rectum. Due to the special location and role of the anus, the skin and tissues around it are exposed to feces, mucus and urine for many years, so if we do not pay attention to hygiene and good living habits, it is easy to develop diseases, such as anal fissures caused by dry stools, hemorrhoids caused by long-term dietary habits, sinusitis caused by bacterial infection, perianal eczema caused by filth stimulation, and anal edema, which often occurs in women. All of these are clinical diseases that are easily caused by the anus and its localization. Note that once a localized anal disease appears, do not feel embarrassed to seek medical attention to avoid delaying the condition.