> For the complete documentation index, see [llms.txt](https://scaleswap.gitbook.io/scaleswap/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://scaleswap.gitbook.io/scaleswap/layer-2-forget-that-expensive-gas/rollup-centric-roadmap-and-the-new-teachers-pets.md).

# Rollup-centric Roadmap and the New Teacher’s Pets

The industry focus has shifted from Plasma as a “one size fits all” solution to several different approaches, [balancing](https://youtu.be/BgCgauWVTs0?t=187) security, scalability, and decentralization. Rollups became the new “teacher’s pet” after Buterin posted his ideas on rollup-centric Ethereum roadmap \[[Magicians](/scaleswap/list-of/references.md)]. Ethereum Foundation explains that “*rollups are solutions that perform transaction execution outside the main Ethereum chain (layer 1), but post transaction data on layer 1*” \[[Richards](/scaleswap/list-of/references.md)].

Rollups can be zero-knowledge (ZKR) and optimistic, the most essential difference between the two is how they deal with proving transactions and disputes. ZK rollups mainly use the SNARK (succinct non-interactive argument of knowledge) method. In contrast, optimistic rollups use fraud-proofs, which trigger longer wait times for an on-chain transaction, yet also enable agility in terms of computational resources required \[[Optimism](/scaleswap/list-of/references.md)].

On top of SNARK (hello, 🕊[Lewis Carroll](https://www.poetryfoundation.org/poems/43909/the-hunting-of-the-snark)), there is also STARK (scalable transparent argument of knowledge) method, of which the [zkSync](https://zksync.io/) project truly stands out \[[Grossman](/scaleswap/list-of/references.md)]. STARK stands out because (according to proponents) it can withstand a quantum computer’s brute force attack, using post-quantum cryptographic algorithms \[[Luciano](/scaleswap/list-of/references.md)].

Optimism uses optimistic rollups, hence the name. However, despite the naming similarity, Optimism is not the only team implementing this type of rollups, the other teams being [Fuel Labs](https://docs.fuel.sh/v1.1.0/Introduction/Welcome.html), [Arbitrum](https://offchainlabs.com/#tech) by Offchain Labs, and [Hubble](https://thehubbleproject.github.io/) \[[Adler Rollups](/scaleswap/list-of/references.md)].