GLOSSARY · BLOCKCHAIN & WEB3
Layer 2
What a layer 2 is: rollups and channels that process transactions off the main chain to scale and cut costs, and how they inherit its security.
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What is Layer 2?
Layer 2 (L2) refers to a set of scaling solutions built on the main blockchain (Layer 1), designed to improve the efficiency, speed and cost of transactions without compromising the security or the decentralization of the base protocol. These solutions work outside the main chain, but rely on it as a settlement and verification layer, thus achieving greater transactional capacity and reducing congestion.
Among the main Layer 2 technologies are:
- Rollups (Optimistic and ZK): group multiple off-chain transactions and publish them on L1 in a compact form. Examples: Arbitrum, Optimism, ZKsync, Starknet.
- State channels: they allow multiple private transactions between parties, publishing only the final result on L1.
- Sidechains: independent blockchains that communicate with L1 through bridges, such as Polygon PoS (although technically not all of them are pure L2).
These solutions make it possible to execute thousands of transactions per second (TPS) with minimal fees and quick confirmations, which is essential for scaling dApps, DeFi, NFT and gaming on networks like Ethereum, where gas costs and L1 throughput are limiting.
Layer 2 represents the ideal technical balance of the blockchain trilemma: maintains the security and decentralization of L1, while optimizing scalability, becoming a key element for mass adoption.
Learn more: What Is Blockchain and How Does It Work? Types, Real Examples and Limits
Explained simply
Layer 2 (L2) is like an extra motorway which is built on top of the blockchain's main road (Layer 1) so that everything works faster and at a lower cost. Thanks to these new lanes, you can send cryptocurrency, make exchanges or use apps without everything getting stuck or costing a lot of gas.
Layer 2: key points
- It is a solution built on top of a blockchain base (Layer 1)
- Improves speed, reduces fees and increases scalability
- Uses technologies such as rollups, state channels and sidechains
- Publishes its data or proofs on L1 to maintain security
- Fundamental to the growth of dApps, DeFi, games and NFTs
Layer 2: advantages
- Much lower transaction costs than on Layer 1
- Increased processing capacity, with thousands of TPS
- Reduced congestion on the main network
- Compatibility with L1 security and liquidity
- Ideal for mass-use products such as DeFi, marketplaces or Web3 games
Layer 2: disadvantages
- Additional technical complexity for users and developers
- Risks of centralization or dependence on sequencers in some cases
- Withdrawal may take time (especially in optimistic rollups)
- Lack of standardization between solutions, making interoperability difficult
- Vulnerability in bridges or interlayer infrastructures
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