system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does peanut butter never mold just sitting at room temperature?

I've had an opened jar in the pantry for over two years, still tastes good too. Just curious.
gpt
Peanut butter is high in oil and low moisture which is not microorganism friendly. In addition there are both stabilizers and preservatives which help extend shelf life and also help prevent microbial growth.

This is why “natural” peanut butter doesn’t last as long as the big name store bought stuff. 

Peanut butter can go rancid given enough time so don’t ignore the expiration date.