# Polygon: What is Plonky2? Why is it Important?

Polygon made headlines recently when it announced its zero-knowledge EVM (zkEVM), an Ethereum-compatible scaling solution. This week, Polygon announced that it had open-sourced its zero-knowledge proof systems Plonky2 and Starky. Both of these systems are dual-licensed under the MIT license and Apache2.

But, there are questions among investors and fans about what these systems are. With that said, let’s take a look at…

### What is Polygon’s Plonky2 system?

The Plonky2 system was introduced in early January of 2022. Polygon aims to use zero-knowledge proofs to scale Ethereum to a billion users. Plonky2 is a recursive SNARK (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge). This system is claimed to be a hundred times faster than others out there.

Recursive zero-knowledge proofs, according to Polygon, were mainly theoretical in 2014. It took around 120 seconds to create them in 2019, which decreased to 60 seconds in 2020. This year, Plonky2 will enable the generation of such proofs to take just 0.17 seconds.

Let’s say we wish to demonstrate the validity of 1,000 transactions. Simultaneously validating 1,000 transactions with a single proof would be costly and time-consuming. Instead, we may use 1,000 machines to produce 1,000 proofs simultaneously. Next, we may create a layer of recursive proofs, each of which verifies two transaction proofs, and recursively aggregate these transaction proofs. This method is repeated until only one proof that can validate 1,000 transactions is left.

### Why is Plonky2 important?

Recursive proofs are essential for scalability. Moreover, the recursive method can be more decentralized, quicker, and less resource-intensive.

Moreover, Plonky2 is natively compatible with Ethereum. According to Polygon, it will take around 1 million gas to validate a plonky2 size-optimized proof on Ethereum. Moreover, the plonky2 proof’s verification cost is expected to fall between 170-200k gas, making it the quickest and least expensive proving method on Ethereum.

Polygon outlined its commitment to assisting ZK scaling last year. This was a significant turning point in the development of Ethereum scaling as Polygon went from offering a crucial answer for the present to creating the future. Plonky2 is a significant advancement for the whole space and a critical milestone for this quest.

ZK L2s have benefitted from significant hype, yet existing approaches rely on ineffective cryptographic primitives that restrict scalability. Plonky2 allows the Polygon ecosystem to construct the most effective and scalable L2s. In the end, L2s will compete on throughput and cost.