system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is happening when you get a random "itch", and why does "scratching" it give us that weird satisfying feeling?
gpt
Basically an itch is when something very small ie: a dust particle, a dust mite, lands on your skin. When this happens you have very sensitive nerves that trigger that itching feeling so that you remove the intruder. When you scratch two things happen you either remove it and the receptors stop giving you that relief feeling or the scratching makes you feel more pain than the itching sensation so you ignore it. That is why sometimes you scratch it kinda stings and then itches again because the pain was a temporary relief. 

Source: a friend of mine is a doctor and we had long talks over the summer over medical things and itching came up, also looked at WebMD to make sure her story was straight.