Thread by @HenriLieutaud

First week working @starkware! So here is me trying to ELI5 what we do.
ZK rollups are a scaling solution for Ethereum. This means they allow you to do more, with less.

More computation, for less gas on Ethereum.
This can mean more volume (think @dydxprotocol , where transaction are very cheap) or more complexity (you can code stuff the EVM can not handle and explore new things)

https://twitter.com/guiltygyoza/status/1452311405437366281?s=20

The way they work is the following.
In Ethereum, all the participants in the network (node) agree on a certain “state”. Think of a big spreadsheet that holds all the balances, for all users, in every token, etc.

Nodes agree on state by sharing the instructions to move the state of block N to state N+1.
So going back to our spreadsheet image, they share something like “Take the content of cell A3, multiply by 4, add B5, then put it in cell D5"

This means that the N+1 value for each cell is computed by each node. A lot of the work is redundant; but is necessary for every one to agree on a common state.

With ZK rollups, instead of every Ethereum node sharing computing instructions, nodes share a state difference. Think “update cell D5”.
They also share a proof, which is a cryptographic value with nice properties.

The proof allows each node to verify that the provided state (with D5 updated) is valid, in the sense that it followed the predefined instructions.
That way, nodes can agree on a common state, without everyone having to redo the computation

The cool thing is that it is much cheaper to do the verification than the computation; and that both do not grow at the same rate. If you do a 10x harder computation, your proof will NOT be 10x harder to verify, it’ll be much easier.

So it puts the burden of execution on a single node instead of the whole network. Which is cool!
Building software to do all of this is not easy, and it takes time.
@Starkware is building a ZK rollups software stack. We have two products:

#Starkex, which is a zk rollups that allows “simple” ERC20 or ERC721 behaviours (mostly trading). It was released over a year ago, and has high profil projects using it (@dydxprotocol , @deversifi , @Immutable, @SorareHQ )

#Starknet, which is a general purpose ZK rollup network, that allows the execution of any kind of programs, and their verification by Ethereum. Starknet has been on testnet since June, and the Alpha will hit mainnet in November

And that's about it.
Are you a dev, looking to learn more about these things?
Get in, the water's warm and the party is just getting started