What is the POSIX OS?

Question

I was just messing with the system functions in Python and I found this, the API that Android and Linux use is POSIX. But what is it
https://code.sololearn.com/c5iQEPKeZhEc/?ref=app

Answer 1

𝕵𝖆𝖓 𝕸𝖆𝖗𝖐𝖚𝖘 MacOS and Android are based on UNIX, not Linux. Because Linux itself is based on UNIX

Answer 2

𝕵𝖆𝖓 𝕸𝖆𝖗𝖐𝖚𝖘 I meant that Linux is just like UNIX. I think you took it the wrong way or I didn't explain it well.