They are blood veins that are swollen. When they are inside they tend not to be painful but they will bleed.
External ones can be painful and itchy.
Who gets hemorrhoids Anyone can get hemorrhoids. Some sort of bleeding is usually one of the first signs of hemorrhoids, but if you're noticing blood, you should not make any assumptions. Other medical conditions, such as fissures, fistulae, abscesses or just irritation of the anus can have some of the same symptoms but are treated differently. Treatment Hemorrhoids aren't very serious and symptoms often go away on their own. If they are being aggravated by constipation, AAFP recommends increasing the amount of fiber in your diet.