# Types of protocols that may support Bitcoin scaling We have seen the following protocols being used to scale Bitcoin. * Federations: Custodial protocols (e.g. Fedimint) or blockchains operated by permissioned federation members (e.g. Liquid) * State channels: Multi-signature contracts where parties can perform transactions while the channel is open * Sidechains: Permissionless consensus protocols (blockchains) that exist to provide more functionality to BTC the asset, or are merge-mined with Bitcoin, or do both. * Sidechain rollups: Rollups that use sidechains for DA and additionally receive settlement assurances from sidechain consensus * Validiums or Optimiums: Blockchains that post DA somewhere but have a trustless BTC bridge. * This is not currently possible. Blockchains may be pseudo-validiums (or optimiums) if they have a BitVM bridge program, but no implementation of this is currently live. * Rollups: Blockchains that post DA to Bitcoin (and have a trustless BTC bridge) * Rollups *can* have trust-minimized validating bridges (that may also validate ZK-proofs) with something like a BitVM bridge program. No implementations of this are currently live. The requirement for being a rollup is using Bitcoin as the DA layer. * Other: Client side validation protocols, Taproot assets, L3s ### Notes * We classify rollups that settle to other blockchains that are not merge-mined, or don't use Bitcoin for data availability, as sidechains. * Alternative Layer 1 blockchains are not sidechains because they do not exist to scale Bitcoin. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://bitcoin-layers.gitbook.io/bitcoin-layers/types-of-protocols-that-may-support-bitcoin-scaling.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.