# FAQ

1.What's Data Availability(DA)?

DA not only includes data storage, but also needs to ensure that any node can access the data. After Layer 2 Rollup, the Ethereum expansion solution, executes transactions and submits transactions, the verification node needs to verify the transaction data, and only the transactions that pass verification will be finalized by Layer 1. The premise of the verification process is to be able to access transaction data. Therefore, transaction data can be accessed by any node, thereby facilitating the process of verifying the correctness of transactions is called data availability. For more details, please refer to: https://ethereum.org/en/developers /docs/data-availability/.

2.What's Memolabs?

[Memolabs](https://memolabs.org/) is a laboratory focusing on researching and scaling decentralized cloud storage technology applications. Our mission is to build a reliable infrastructure for Web3.0 and develop robust decentralized storage and application tools.

3.What's Mefs?

Mefs is a low-cost, reliable and secure decentralized cloud storage system developed by Memolabs, which takes advantage of edge storage devices and the non-tampering and decentralized characteristics of blockchain. For specific information, please refer to [Memolabs](https://memolabs.org/).

4.What's Meeda?

Meeda is a data availability solution launched by Memolabs for Ethereum Layer 2, especially Optimistic Rollup, it is low-cost, safe and reliable.

5.How to combine Ethereum Layer2 with Meeda?

For details, please refer to the `Node/Op Node & Meeda` and `Developers/Connect L2 to Meeda` sections for details.
