Celestia is an innovative blockchain platform that pioneers the modular blockchain architecture, enabling scalable and flexible data availability solutions apart from traditional monolithic blockchains. It was conceived to address scalability issues and increase the efficiency of shared networks by decoupling consensus and data availability layers. This approach allows for diverse use cases and enhances transaction throughput without compromising security. Originating from the intriguing work on data availability sampling, Celestia is designed to accommodate multiple Layer 2 solutions, enabling developers to deploy customisable blockchains tailored to specific requirements without the constraints of consensus mechanisms. By focusing on rollup-centric ecosystems, Celestia fosters a more scalable and interconnected blockchain ecosystem, offering a foundation that supports both decentralisation and efficiency in handling vast amounts of data.