A hemorrhoid is an enlarged blood vessel within the anal canal which has become swollen or inflamed due to an increase in venous pressure forming masses or clumps of tissue within the anal canal that contain blood vessels. The anal canal is the last four centimeters through which stool passes as it goes from the rectum to the outside world. Bleeding from hemorrhoids can occasionally be severe. If the hemorrhoid originates at the top of the anal canal, it is referred to as an internal hemorrhoid, If it originates at the lower end of the anal canal near the anus; it is referred to as an external hemorrhoid.