upgrades in 2021. The first was "Berlin", implemented on 14 April 2021. The second was "London", which took effect on 5 August. The London upgrade included Ethereum Improvement Proposal ("EIP") 1559, a mechanism for reducing transaction fee volatility. The mechanism causes a portion of the ether paid in transaction fees for each block to be destroyed rather than given to the miner, reducing the inflation rate of ether and potentially resulting in periods of deflation. On 27 August 2021, the blockchain experienced a brief fork that was the result of clients running different incompatible software versions. Ethereum 2.0 Ethereum 2.0 (Eth2) was a set of three or more upgrades, also known as "phases", meant to transition the network's consensus mechanism to proof-of-stake, and to scale the network's transaction throughput with execution sharding and an improved EVM architecture. The first of these three upgrades, also known as "phase 0", launched the proof-of-stake Beacon Chain on the 1st of December, 2020. Following the realisation that the Beacon Chain would be delivered much earlier than the later phases of the Eth2 roadmap, proposals were made for an "early Merge", expediting the delivery of proof-of-stake to Ethereum. Most importantly, the early Merge would not require any migration from Ethereum’s applications or its users, and would continue using the heavily battle-tested mainnet Ethereum clients in conjunction with the new proof-of-stake consensus clients. In early 2022, the “Ethereum 2.0” terminology was deprecated in an effort to highlight the existence of only one Ethereum network and one ether cryptocurrency. As a result of the effort, the Eth1 blockchain was renamed to the “execution layer”, and its associated Eth1 clients were reclassified as execution clients. Similarly, the Eth2 blockchain was renamed to the "consensus layer", and its associated Eth2 clients were reclassified as consensus clients. The switch from proof-of-work to proof-of-stake has cut Ethereum's energy usage by 99%. However, the impact this has on global energy consumption and climate change may be limited since the computers previously used for mining ether may be used to mine other cryptocurrencies that are energy-intensive. Design Ethereum is a permissionless, non-hierarchical network of computers (nodes) that maintains a database containing the ETH balances and other storage values of all Ethereum accounts, known as the "state", and processes state-altering transactions. Approximately every 12 seconds, a batch of new transactions, known as a "block", is processed by the network. Each block contains a cryptographic