Is AVAX under Ethereum?

I'm curious about AVAX. Could you clarify if it falls under the umbrella of Ethereum? I've been hearing a lot about blockchain technology and cryptocurrencies lately, and I'm trying to wrap my head around the various projects and platforms out there. Ethereum, of course, is a well-known smart contract platform, but I'm not entirely sure about AVAX. Is it built on Ethereum? Or is it a separate entity? I'm just trying to get a better understanding of the crypto ecosystem, and your expertise in this area would be invaluable.