Internal piles develop inside your anal canal, but they can hang down outside your anus. Internal piles can be graded according to how far they protrude, if at all, from your anus.
First degree piles are swellings on the inside lining of your anal canal. They may bleed but can't be seen from outside your anus.
Second degree piles are larger than first degree piles. They come out of your anus when you have a bowel movement, but go back inside on their own afterwards.
Third degree piles hang down from your anus and only go back inside when you push them in.
Fourth degree piles permanently hang down from your anus and you can't push them back in. They may become very swollen and painful if the blood inside them clots.