ELI5: I understand how my body heals itself on the outside, but can someone explain what the process is on the inside. Not just like a simple cut, but more like a sore on the stomach lining or even a gunshot wound.

Had a Shower thought, but I actually wanted to understand it. I'm literate so go ahead and give me the actual process don't hold back.

Edit: First comment covered a small, but helpful amount of Information. I would like to go (deeper ;) ) more in depth. I am quite intrigued by this function in my body.