Hemorrhoids are swollen veins in the lowest part of your rectum and anus. Sometimes the walls of these blood vessels stretch so thin that the veins bulge and get irritated, especially when you poop. Swollen hemorrhoids are also called piles. Hemorrhoids are one of the most common causes of rectal bleeding. They're rarely dangerous, but you should see your doctor to make sure you don’t have a more serious condition. Hemorrhoids often go away on their own, but treatments can also help.
Internal hemorrhoids are far enough inside your rectum that you can't usually see or feel them. They don't generally hurt because you have few pain-sensing nerves there. Symptoms of internal hemorrhoids include:
Blood on your poop, on toilet paper after you wipe, or in the toilet bowl
Tissue that bulges outside your anal opening (prolapse). This may hurt, often when you poop. You might be able to see prolapsed hemorrhoids as moist bumps that are pinker than the surrounding area. These usually go back inside on their own. Even if they don't, they can often be gently pushed back into place.