Internal hemorrhoids involve the veins inside your rectum. Internal hemorrhoids usually don't hurt but they may bleed painlessly. Sometimes, an internal hemorrhoid may stretch down until it bulges outside your anus. This is called a prolapsed hemorrhoid. A prolapsed hemorrhoid will go back inside your rectum on its own, or you can gently push it back inside.
External hemorrhoids involve the veins outside the anus.
They can be itchy or painful and can sometimes crack and bleed. If a blood clot forms, you may feel a tender lump on the edge of your anus. You may see bright red blood on the toilet paper or in the toilet after a bowel movement. One of the main causes is straining when you're trying to have a bowel movement. This may happen if you're constipated or if you have diarrhea.