A normal person will have a stool every day. Some people have a stool 2 to 3 times one day or one time every 2-3 days,If the characters of stool is normal, the daily average weight of stool is 150 ~ 200 g , containing 60% to 75% of moisture. Diarrhea is a common symptom, which means that the times of stool are noteworthy more than the usual frequency. Feces are thin and the water is increased. The daily weight of stool is more than 200 g or includes undigested food or purulence and mucus. Diarrhea is usually accompanied by the following symptoms: an urgent sense of having stool, discomfort of anus and incontinence. Diarrhea can be classified as acute and chronic diarrhea. Acute diarrhea is acute and the courses will last two to three weeks. Chronic diarrhea is the recurent diarrhea which will last more than two months or intermittent period is within 2-4 weeks. ]]>