Verkle Tries are a type of data structure similar to Merkle Patricia Trees (MPT), which is the data structure used in Ethereum today. While Verkle Tries utilize a tree-like structure similar to MPT, a key difference is each node uses a special type of hash (called a vector commitment) to commit to children nodes. These vector commitments provide several important, long-term benefits, and help pave the way for statelessness in Ethereum.

Note: Both Verkle Tries and Merkle Trees serve a key purpose in blockchain networks — providing data in a format that allows for network participants to easily verify network state (needing only a short proof, aka “witness”, and the root of the tree).

Because it can help Ethereum achieve statelessness! The key benefit of the vector commitments used in Verkle is that they allow for much smaller proof sizes (called witnesses). Instead of needing to provide hashes of all "sibling nodes" at each level, as in Merkle Trees, the prover needs only to provide all parent nodes (plus an extra proof, called an optional) along the paths from each leaf node to the root. Since we no longer need to provide all sibling nodes, we can structure Verkle Tries to be much wider than Merkle Trees. All of this allows for much smaller witness sizes.

What’s so great about small witness sizes? Large witnesses are the key problem standing in the way of statelessness. When witnesses (proofs) are small enough, they can be contained within each block. This allows for the verification of any block using only what’s contained within the block itself.

The general principle of “statelessness” is that nodes verifying blocks no longer need to store state. See this writeup from Dankrad Feist on why statelessness is a worthy goal.

How do we actually get from the current Merkle world to Verkle?

See this writeup on potential migration paths, which currently include four options:

Specific things you can do right away:

Elephants have been known to uproot trees :)

The motivation can be summarized as follows:

That might be the case, yes. See list of “Open Questions” in the Dashboard below. Help is appreciated!

Today, to validate the chain, you need to have a fully synced node containing all the state. This is needed since, currently, blocks don’t have all the required state to execute that block due to the cost of generating a witness using the current Merkle Patricia Trie.

With Verkle Trees EIP, blocks can be self-contained execution units which allow them to be verified without requiring any extra information, in particular the full state of the chain.

There’s currently no defined date, but targeting sometime in 2024

This number is still undecided since it’s mostly a balance between overall migration duration speed (good!) and rising the bar of hardware requirements for following validators (bad!). See the “Open Questions” section of the Dashboard below.