Celestia is a modular consensus and data availability layer that allows anyone to build and deploy their own blockchain without having to worry about the overhead of creating their own consensus network. Currently planning on a testnet release sometime this year, currently the network only supports a private devnet. The Celestia layer is meant to simply order transactions and verify that the data published in said transactions is available (known as the 'data availability layer'). This allows other blockchains to build on top of Celestia to improve scalability and interoperability.