> For the complete documentation index, see [llms.txt](https://docs.merlinchain.io/merlin-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.merlinchain.io/merlin-docs/about-merlin/key-modules.md).

# Key Modules

Merlin Chain operates as a Layer 2 solution within the Bitcoin network, employing a combination of innovative technologies to enhance scalability, efficiency, and functionality. There are **5 key modules** of Merlin Chain:

* [ZK-Rollup Network](/merlin-docs/about-merlin/key-modules/zk-rollup-network.md)
* [Decentralized Oracle Network](/merlin-docs/about-merlin/key-modules/decentralized-oracle-network.md)
* [Data Availability](/merlin-docs/about-merlin/key-modules/data-availability.md)
* [Two Step Zero-Knowledge Proof Submission Mechanism](/merlin-docs/about-merlin/key-modules/two-step-zkp-submission-mechanism.md)
* [Fraud Proofs Based on Bitcoin](/merlin-docs/about-merlin/key-modules/fraud-proofs-based-on-bitcoin.md)