1/ What is modularity?

The essence of modularization is to break the "impossible triangle" and improve performance without increasing the cost and burden of node hardware to avoid centralization. To this end, the four layers of the Layer 1 protocol are:

1) Consensus layer 2) Settlement layer 3) Data layer 4) Execution layer

Split to achieve the purpose.

2/ What is#Celestia?

Celestia separates the data layer and builds it on Cosmos, providing only consensus and pluggable data availability services. The business model is toB, and Layer1 and Layer2 can use Celestia services. The source of income is to charge the public chain running on it. It does not provide smart contracts, so dApps cannot be built directly on it. Celestia has also developed the Ethereum Layer2 project #Celestiums.

3/ What is Data Availability (DA)?

When a new block is generated on the chain, the full node must download the block data, perform complex calculations, and verify the validity of all transactions in the block. If the block producer does not provide data, the full node cannot verify. As the amount of data increases, the hardware requirements for full nodes become higher and higher, and the number of nodes that can meet the requirements decreases, the network will become centralized. Therefore, Rollup expansion was created to separate the execution layer from Ethereum.

4/ The key to Rollup expansion is to use a centralized sequencer to compress data and publish it to all Ethereum nodes. The main network verification node can verify the data through fraud proof (Optimistic) or validity proof (ZK). Although the data is compressed, the problem of data availability still exists.

One solution is sharding, represented by Ethereum DarkSharding. Each shard verifies different data and is sorted by the beacon chain. Another is #Celestia. Using erasure coding, you only need to download a small fragment of a block to check whether all the data of a block has been published. At the same time, you can also use the fragment to restore all the data.

5#Celestiahas just completed a $55 million financing, with a valuation of $1 billion. Investors include BinanceLabs, Polychain, Coinbase, Jump, FTX, Delphi, Spartan, etc.

Summary of study materials:

https://pickle-flute-cbc.notion.site/Celestia-b126520b90a14d66b890fd437aad1c4f