At the moment you are reading this post, Ethereum is probably already after the technological transformation from Proof of Work technology to Proof of Stake technology. This is undoubtedly the most unprecedented and most important event in the entire history of the Ethereum ecosystem, and in my opinion, the most important for the entire crypto world in terms of the opinions of those less interested.
In proof-of-work, verifying cryptocurrency transactions is done through mining. In proof of stake, validators are chosen based on a set of rules depending on the “stake” they have in the blockchain, meaning how much of that token they commit to locking up to have a chance to be chosen as a validator. In either case, the cryptocurrencies are designed to be decentralized and distributed, which means that transactions are visible to and verified by computers worldwide. [1]
Unfortunately, the Proof of Work technology on which the first and most popular cryptocurrency, Bitcoin, is based, is environmentally unfriendly and requires very large amounts of energy. There is a reason why the largest number of Bitcoin diggers are in countries where energy is cheapest, namely the United States, China and Russia.
Proof of Stake technology requires much less energy, and gas taxes per transaction are negligible, often the equivalent of a few cents. Given that in a dozen hours or so, the second largest cryptocurrency will start using it, it will be a milestone against mass adoption and a counter-argument to many people who have taken the environmental impact of cryptocurrencies as a disadvantage.
References:
[1] https://www.coindesk.com/learn/proof-of-work-vs-proof-of-stake-what-is-the-difference/