The transition from Proof-of-Work (PoW) to Proof-of-Stake (PoS) is the most important and complex upgrade in Ethereum's history. The process, which has been ongoing for seven years, has reached the finish line.
Today, September 15, 2022, the core network of Ethereum, the second largest cryptocurrency by capitalization, officially switched to the Proof-of-Stake algorithm.
The activation took place on block #15537394.

This is what the first block on the PoS looks like:

This means that now the era of ETH mining is over and it's time for stacking (making the network work with validators using the coins locked in the deposit contract).
In parallel, the hash rate and complexity are completely zeroed out - this means that miners have completely shut down their equipment, mining ether with special equipment no longer exists. (The participation rate of validators exceeded 96% with 66% allowed, according to Nansen).

Vitalik Buterin confirmed the successful merger on his Twitter:
"We have reached the goal. This is an important moment for Ethereum".

The transition from Proof-of-Work (PoW) to PoS is the most important and complex upgrade in the history of blockchain. ConsenSys co-creator and founder Joseph Lubin called the upgrade the third major event in the industry after bitcoin and the creation of Ethereum.

Ordinary Ethereum users will not notice any tangible impact from switching to PoS.
Users of Ethereum as a smart contract platform will only notice the regularity of blocks appearing (exactly 12 seconds instead of the current ~13.5 seconds and a wide variation from 1 to 60 seconds). Holders of ETH as a cryptocurrency will enjoy a 99% reduction in network power consumption.