Before we understand what the merge really is we first have to understand the difference between PoW and PoS and how Ethereum will transfer from the former to the latter.
I’m assuming that the vast majority of users here understand this so you can skip this part if you want.

– PoW and PoS

As of the writing of this post, Ethereum currently runs on PoW (proof of work). The main goal of the merge is for Ethereum to move over to PoS (proof of stake).

The main difference between these two is that with PoW the network is secured by miners that have to purchase and run Ethereum mining hardware. This model has proven to be extremely inefficient since miners have to consume electricity in order to issue new blocks. This is exactly why Ethereum is notorious for being slow and expensive.

With the PoS model, on the other hand, the network is secured by validators who instead stake ETH in order to validate network activity. With this model, power consumption decreases dramatically.

With PoS, the network becomes more efficient, more secure, and can start benefiting from further upgrades most prominent of which is Sharding (which will be mentioned later on)

– What is the “merge”?

When people talk about “the merge” they’re actually talking about two-step of which the actual merge is one of them.

The first step is launching the Beacon Chain which was already done successfully in December of 2020.

The main goal behind this was to be able to test a chain running in parallel with the already existing PoW network without causing any disruption.

Another reason for this was to give time for stakers to stake enough ETH to secure the new network when implementing the actual merge

The second step is what we call the marge and it's what everyone is talking about right now.

The merge is simply the act of merging the consensus layer of the Beacon chain with the EVM state of the Ethereum PoW chain.

– What happens when the merge is fully implemented?

For starters, the power consumption needed to execute transactions and everything else on Ethereum dramatically decreases from what it was with PoW.
In fact, it will decrease by almost 99.95%.

This is great for multiple reasons:

Firstly this makes Ethereum ESG compliant which is great for institutions overall especially ones that are regulatory driven. This will most definitely help boost mainstream adoption since many more global institutions will start exploring the Web3 space.

Second of all, a lot of the environmentally driven critics will finally shut down their arguments about NFTs, DeFi, and all Ethereum activity overall ruining the planet.

Third and finally, the merge will open up the groundwork for new updates included in the Ethereum roadmap that all of which combined will improve Ethereum overall, most important of which is Sharding.

– Misconceptions about the merge and how Sharding is related to that

The merge on its own will not make Ethereum gas fees lower. In fact, NOTHING will make gas on the Ethereum chain itself lower.

The Ethereum roadmap is not working on lowering gas fees on the chain, but instead is working on improving and integrating rollups and L2s in order for THEM to help with gas fees and traffic overall.

The L2 wars are more competitive than ever before but I think this is good news for Ethereum overall because it rewards innovation and new tech. But I’m personally biased towards Polygon as of now.

Speaking of which, I still have no idea how people still fall for this misconception that L2s and scaling solutions will be irrelevant with “ETH 2.0” (which isn’t even a thing anymore) even though Vitalik himself talked about it at the Polygon ZK summit back in 2021 where he discussed the importance of rollups on Ethereum

Ever since then, we’ve seen a flurry of development in the rollup scene and most notably the ZK-rollup with the recently mentioned Polygon leading the way with their open source zkEVM.

They already have 8 multipurpose Ethereum scaling solutions all of which will become even more efficient with Sharding introduced.

– What is the main risk behind the merge?

Any upgrade to any new technology comes with risks. This isn’t “FUD”. These are simply very improbable yet still realistic scenarios that may compromise the security of the PoS network.

Right now the biggest concern is a DOS scenario.

Since validators are the ones that are securing the chain, the network can technically be in danger of something called Network In Denial of Service (DOS) where if the attacker can know exactly which proposer is next in line they can try to DOS said proposer and strip them of their slot. The transactions that come with this slot can now be picked up by the attacker.

This is a very improbable scenario and already has solutions most popular of which is SSLE. Its basically complicated cryptography that prevents the attacker from knowing which proposer is next in line

I hope this post clears up some misconceptions, questions, and concerns overall. I’d be happy to answer any questions in the comments.