Is Ethereum Classic the original Ethereum?

Could you please clarify something for me? I've been hearing a lot about Ethereum Classic and I'm wondering, is Ethereum Classic actually the original version of Ethereum? Or is it a spin-off or a modified version of some sort? I'm trying to understand the history and relationship between the two. Could you explain the difference between them, and maybe provide some context as to how Ethereum Classic came about? It would be really helpful for me to get a clear picture of this. Thank you in advance for your assistance.