After several years of preparation, the merger was completed on September 15 and ethereum transitioned from Proof of Work (PoW) to Proof of Stake (PoS).
This implementation brought several benefits, including a 99% reduction in network power consumption and created a foundation for segmentation to improve scalability in future hard forwards.
The merger also began with EIP 1559, which was deployed in a hard fork in London in August 2021. This simplified the market mechanism for Ethereum fees. This included splitting the fee into a base fee and a tip, with the base fee being burnt.
The post-merger PoS mechanism touted the burning of base fees as a deflationary mechanism that would reduce token issuance by as much as 88%.