The Role of Nerves in Pain

When does a non-painful stimulus become something painful? Is there a kind of trigger where me just touching my wrist doesn't do anything but if I was to prick it with a pin I would feel pain. Within the skin itself you have different type of nerve fibers, there's nerve fibers that respond to heat so those are also sensitive to chili peppers which is why chili pepper feels like a burn. We have ones for itch, we have ones for touch. Pain is good right, it's an evolutionary advantage, it's something our body needs to do to stop us causing ourselves more injury.