Is The Graph built on Ethereum?

Could you please clarify whether The Graph is indeed constructed on the Ethereum blockchain? I'm curious about the technological foundation of this project and how it interacts with the Ethereum ecosystem. I've heard rumors that it's based on Ethereum, but I'd like to have a more definitive answer. Could you elaborate on the relationship between The Graph and Ethereum, and perhaps explain why this choice was made for the project? Thank you for your time and assistance in clarifying this matter.