Ethereum 2.0 is an upgrade to the original Ethereum blockchain, aimed at improving its scalability, security, and sustainability. It introduces a new consensus mechanism called Proof of Stake (PoS), which allows users to validate transactions and create new blocks by holding and "staking" their Ether instead of using energy-intensive mining. This upgrade is being implemented in multiple phases, with the first phase, known as Phase 0, launched in December 2020. Ethereum 2.0 is expected to significantly reduce energy consumption and increase transaction speeds, making the network more efficient for developers and users alike.