Is Avalanche an Ethereum fork?

Excuse me, I've been hearing a lot about Avalanche recently and it seems to be quite popular in the cryptocurrency world. However, I'm a bit confused about its origins. Could you clarify for me whether Avalanche is indeed an Ethereum fork? I've read some conflicting information online and I'm trying to get a clear understanding of its relationship, if any, with Ethereum. Could you please elaborate on this matter? Your expertise in this field would be greatly appreciated. Thank you in advance for clearing up this confusion for me.