# Celestia docs

  Celestia is a modular data availability network. Rollups publish transaction
  data to Celestia while choosing their own execution and settlement layers.
  Use these docs to learn how data availability works, post and retrieve blobs,
  and run a node on Mainnet Beta or the Mocha testnet.

[Learn](/learn/celestia-101/data-availability): Understand modular blockchains and Celestia's architecture, including data availability sampling and how rollups use blobspace.

[Build](/build/post-retrieve-blob/overview/): Post and retrieve your first blob with Go and Rust transaction clients. Follow the guides for signer setup, funding, and testnet examples.

[Operate](/operate/getting-started/overview/): Choose a node type, check hardware requirements, and install Celestia software. Find guides for maintenance, monitoring, and troubleshooting.

[API](/build/rpc/node-api): Explore Celestia Node JSON-RPC methods, authentication, and client libraries. Download versioned OpenRPC specifications from the API reference.