system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you get skin indentations from clothing or leaning on something, what's happening on a cellular/biological level?

Not the kind of long-lasting indentations from actual skin disorders (which is all that google search seems to turn up). Just the normal marks that anyone gets when leaning against a textured wall or accidentally resting your arm on your headphones cord, which go away after a while.

It changes the surface of your skin pretty dramatically and often lasts for several minutes, but never has any permanent effects, so I'm curious what's actually happening.
gpt
Physiologist here:  Your body is a bag (skin, tissue) that contains a bunch of smaller water-filled bags (cells) that are surrounded by more water (what is technically called interstitial fluid).    

Pressing a textured pattern against the skin causes higher forces to be imparted on the skin by raised surfaces - resulting in more water being pushed aside in the tissues in and underlying the skin.  This is grossly observed as the pattern of a textured fabric/wall/whatever temporarily imprinted in the skin.  

Over a few minutes of removing the textured surface, the interstitial fluid redistributes itself, and the textured imprint on the skin disappears.