Rollups are a Layer 2 (L2) scaling solution for blockchains—especially Ethereum—that bundle or “roll up” many transactions into a single transaction. The goal is to reduce congestion, lower fees, and increase throughput on the main (Layer 1) blockchain

Here's how rollups work in simple terms:

1. Batching Transactions: Dozens or hundreds of L2 transactions are aggregated into one.

2. Submitting to L1: A summary of the rollup batch is posted to the main blockchain (L1), usually along with a cryptographic proof.

3. Storing Data: Depending on the type, some transaction data may also be posted to L1 for security and transparency.

There are two main types of rollups:

1. Optimistic Rollups

i). Assume transactions are valid by default.

ii). Fraud can be challenged during a challenge period (usually 1–2 weeks).

iii). Examples: Optimism, Arbitrum.

2. ZK-Rollups (Zero-Knowledge Rollups)

i). Use zero-knowledge proofs to validate correctness immediately.

ii). Faster finality and better scalability, but more complex.

iii). zkSync, Starknet, Polygon zkEVM.

Benefits of rollups:

1. Lower gas fees.

2. Higher throughput.

3. Security inherited from Layer 1 (Ethereum).

I hope you learn something new 

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