system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does our skin leave white marks when we scratch or get scratched?
gpt
The skin is made up of several layers and the top layer is dead (gross right?). Well when you scratch you're scraping a bit of the layer off. This layer is slightly transparent so appears white when not in direct contact with the lower layers.
Hope this helps.