What is the maximum ETH supply?

Could you please clarify the maximum supply of Ethereum, or ETH, for me? I understand that unlike some other cryptocurrencies, Ethereum has a unique mechanism for issuing new tokens, but I'm unsure of the exact cap on the total number of ETH that can ever exist. Is there a specific limit set in place, or does the supply fluctuate based on certain conditions? Thank you for your time and expertise in this matter.