Celestia is a modular data availability network that securely scales with the number of users, making it easy for anyone to launch their own blockchain.

Celestia enables the next generation of scalable blockchain architectures - modular blockchains. Celestia scales by decoupling execution from consensus and introducing a new primitive, data availability sampling.

The former entails that Celestia is only responsible for ordering transactions and guaranteeing their data availability; this is similar to reducing consensus to atomic broadcast.

The latter provides an efficient solution to the data availability problem by only requiring resource-limited light nodes to sample a small number of random chunks from each block to verify data availability.

Interestingly, more light nodes that participate in sampling increases the amount of data that the network can safely handle, enabling the block size to increase without equally increasing the cost to verify the chain.

Data availability answers the question, has the data for this blockchain been published? It is critical to the security of any blockchain because it ensures that anyone can inspect the ledger of transactions and verify it.

Users of a monolithic blockchain usually download all the data to check that it is available.

As blocks get bigger, it becomes impractical for normal users to download all the data meaning that they can’t verify the chain. Modular chains solve this problem by making it possible for users to verify very large blocks using a technology called data availability sampling.

Data availability sampling (DAS) is the new primitive that enables Celestia light nodes to verify DA efficiently. Instead of downloading all data, light nodes only download a tiny portion of each block.

Importantly, DAS allows Celestia to scale with the number of users (light nodes). So, as the light node network grows over time, Celestia can scale to the data throughput needed for millions of rollups without compromising on security for end users.

Rollups are a relatively new type of blockchain. What makes them different is that they offload some of their work to a layer 1 like Celestia. The simple version is that rollups publish their transaction data to Celestia, which gets ordered and made available for rollup users to download. As a bonus, rollups receive some of Celestia’s security.

But rollups on Celestia aren’t quite the same as others. They are convenient to launch like layer 2s with the added sovereignty that layer 1s enjoy. We like to call these blockchains sovereign rollups.

Most blockchains today are monolithic, so it only makes sense to understand what they are before we explain what modular means.

A monolithic chain is a generalist blockchain that performs all tasks. Really, the monolithic approach is “do everything yourself”.

Some blockchains that fall into this monolithic category include Solana and Sui.

We can’t forget that monolithic chains were a big first step. They showed us that you could build all sorts of new applications using blockchains. Once people started building and using apps on them, they ran into some difficulties.

• You can’t build anything you like. Sharing space on someone else’s blockchain limits what you can build for your app.

• Expensive apps. High fees can creep up, making apps unaffordable.

• Access isn’t open to all. Raising capacity usually means fewer people can afford to check that the network is running correctly.

Many of these difficulties make monolithic blockchains difficult to use or miss the reasons why we use blockchains in the first place.

In the last few years, a new approach to building blockchains emerged. That new approach is what people are calling “modular blockchains”. But what are they exactly?

Well, modular blockchains are specialists. They perform only one or two tasks - the opposite of monolithic chains.

Modular chains don’t sit alone, though. Multiple of them combine to perform all the tasks a monolithic chain does by itself. This combination of chains is what we call a modular stack.

There might be some unfamiliar terms in the image above, like data availability or execution. Don’t worry.

You can think about modular blockchains like Lego pieces. You can mix and match Legos to create different structures, just like you can mix and match modular blockchains to create different modular stacks.

In the modular category we have blockchains like Celestia and rollups. Rollups host applications and do many of the same things that monolithic blockchains do. What makes a rollup modular is that it uses another blockchain, like Celestia, to complete the tasks it doesn’t do.

As you can tell, modular chains specialize and work together to do all the tasks a single monolithic chain does. If there’s one thing you should take away about modular and monolithic chains, it’s that:

• Monolithic = generalist

• Modular = specialist

Why is modular an improvement?

You know what modular blockchains are now. But, how do they improve upon the difficulties that monolithic blockchains face?

• Modular chains let you build whatever you want

• Modular chains let you make apps cheap to use

• Modular chains let you create open access for all

Both Celestia and Dymension are innovative blockchain projects exploring modularity to address scalability and flexibility challenges in traditional blockchain networks. However, they have some key differences:

Focus:

Celestia: Focuses on the data availability layer, providing a secure and censorship-resistant way for other blockchains ("execution layers") to store and retrieve data. It acts as a shared infrastructure for these rollups and sidechains.

Dymension: Built as a complete modular blockchain platform. It incorporates the data availability layer (based on Celestia) alongside built-in rollup technology for execution. This creates a unified environment for deploying various applications directly on Dymension.

Architecture:

Celestia: Purely focused on data availability, it leaves consensus and execution to other independent layers. This modularity allows for greater customization and optimization for specific use cases.

Dymension: Integrates multiple functionalities within its core platform. Rollup creation and data availability are bundled, providing a simpler user experience but less flexibility compared to Celestia.

Target audience:

Celestia: Aimed at developers building application-specific execution layers or rollups, seeking a secure and decentralized data availability solution.

Dymension: Targets a broader audience, including developers and users looking for a readily deployable modular blockchain platform with built-in rollup capabilities.

For years, crypto has endured a monolithic blockchain loop. Each new L1 has built a walled-off system, where competition is fierce and zero-sum. This leads to maximalism as they all fight over users in their ecosystems.

Modular blockchains create a collaborative environment with many connected chains. Each new user that a modular blockchain brings in creates value for the whole modular ecosystem, not just a single L1. Modular blockchains collaborate while monolithic L1s compete.

Modularism, not maximalism.