Ethereum 2.0 is a new version of the Ethereum blockchain...

that will use a proof of stake consensus mechanism to verify transactions via staking.

The mining process requires an ever-increasing amount of electricity to verify Ethereum transactions

Proof of work systems devour a tremendous amount of electricity, 

For Example, Bitcoin mining currently consumes electricity at an annualized rate of 127 terawatt-hours (TWh).

That’s currently higher than the power consumption of the entire country of Norway.

ETH currently has an annual power consumption roughly equal to Finland,

Since April 2022, Ethereum has been running two parallel blockchains,

one that operates using proof of work, and a test chain that operates via proof of stake.

The merge will combine the legacy Ethereum Mainnet blockchain (ETH1) and the new Beacon Chain (ETH2) into one unified blockchain.

Ethereum developers recently ditched the ETH1 and ETH2 terminology over concerns

that it would confuse users ahead of the merge.