What does max supply mean in Crypto?

Could you please elaborate on the concept of "max supply" in the realm of cryptocurrencies? Specifically, how does it differ from other metrics like circulation supply or total supply? Is it a fixed number that cannot be exceeded, or is it subject to change under certain conditions? Understanding this fundamental term seems crucial for investors and enthusiasts alike, as it could have significant implications for the long-term value and scarcity of a particular digital asset. Could you provide a concise yet comprehensive explanation?