What is diarrhea?
A general definition: an increase in frequency (several times per day) of bowel movements which are often looser and watery stools than usual. Most people have diarrhea several times per year. Diarrhea often goes away by itself quickly (in one or two days) without any special treatment. If it doesn't go away then this may be a sign of a more serious underlying problem which makes it necessary to seek treatment.
People with diarrhea are at risk of becoming dehydrated. With the increased and watery bowel movements it is more difficult for the body to retain enough fluids to stills function properly. This can seriously affect the health of people if left untreated, particularly with children and the elderly.