Although piles develop from inside your anal canal, they can hang down out of your rectum. They are graded as follows: 1st degree piles are swellings on the inside lining of your anal canal. They may bleed but can't be seen from outside the anus. 2nd degree piles are larger and stick out prolapse) from the anus when you have a bowel movement, but return on their own after wards. 3rd degree piles are similar, but hang out from your anus and only return inside when pushed back in. 4th degree piles permanently hang down from your anus and you can't push them back inside. They may become extremely swollen and painful if the blood in them clots. External piles are swellings that develop from below the anal cushions. They can be more painful than the other types of piles.
Attribution: BUPA