Ethereum developers have finalized the details of the upcoming hard fork upgrade, known as "Dencun." The upgrade will include five Ethereum Improvement Proposals (EIPs) that aim to increase data storage and reduce fees. The main feature of the upgrade is EIP-4844, also known as proto-danksharding, which will scale the blockchain by creating more space for data. The hard fork is expected to take place by the end of 2023, and developers can now begin rigorous testing of the upgrade.