system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What are 1st, 2nd, 3rd, 4th degree burns? How dangerous/harmful are each?
gpt
1st - 4th in terms of least - most dangerous.

The categories are basically how deep in your skin the burn goes. How many layers it affects.

1st degree affects the top layer, it won't blister, just be a bit red for a while. Mild sunburn for example.

2nd degree affects the top two layers. You might get swelling, the burn will be bright red and shiny, and will blister.

3rd degree completely destroys the top two layers. It may not hurt because you've cauterised the nerves, will definitely require hospital treatment, and will definitely scar.

4th degree are the worst. All layers of your skin are destroyed, and the burn may even damage muscle, tendons and bone. Life-threatening.