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A comprehensive guide to Layer 2 scaling solutions super easy to understand for beginners

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1. What is Layer 2?

The impossible trinity of blockchain:

decentralization, security, and scalability -> Layer 2 scaling solutions

- Layer 2: built on Layer 1 -> inherits the security of Layer 1

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2. Types of Layer 2 solutions

- State Channel: like opening a tab at your local coffee shop. You track your drinks from the main ledger, then pay at the end of the week.

- Rollup: processes hundreds of transactions -> aggregates them into 1 transaction -> Layer 1

- Optimistic rollups: fraud proof + Store data on Ethereum

- Zero-knowledge (zk) rollups: validity proof + Store data on Ethereum

- Plasma (child chain): fraud proofs + separate blockchain anchored to Ethereum

- Validium: validity proof + DOES NOT store transaction data on Ethereum

- Sidechain: independent blockchain running parallel to Layer 1

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3. Comparing Optimistic Rollup and ZK Rollup

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ZK Rollups

- Zk proof + does not disclose sensitive information

- Transactions: Fast

- Cost: computational proof -> higher

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Optimistic Rollup

- Assumes transactions are valid by default -> challenge -> fraud proofs

- Transactions: delayed

- Cost: low

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4. Benefits of Layer 2:

- Low fees

- Ensures security

- Increases usability

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5. Layer 2 ecosystem

Growing very robustly, more and more new projects are emerging. Some notable projects:

- Optimistic rollups:

+ OP Stack: OP, Base, Blast, Metis, WLD, Cyber,..

+ Arbitrum: ARB, Paralle

- Zk rollups: Zksync, Starknet, Linea, Scroll, Taiko,...

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