Ether (ETH) is the native cryptocurrency of the Ethereum blockchain. It serves multiple functions within the Ethereum ecosystem. It is primarily used as a digital currency for value transfer and paying transaction fees on the network. Additionally, Ether acts as an incentive for miners who maintain the blockchain's security and consensus. It also serves as a utility token within the Ethereum ecosystem, used for interacting with smart contracts and decentralized applications (dApps) built on the platform.