Blockchains are very secure, but that comes with trade-offs. Their security can reduce speed and increase transaction costs. Many blockchains cannot handle thousands of transactions at once. Improving scalability often weakens security and decentralization. This is called the blockchain trilemma, and different methods exist to address it.

Sometimes, faster transactions are needed, especially for blockchain apps or projects needing smooth interactions. Blockchain rollups solve this by helping networks handle transactions more efficiently.

But what are blockchain rollups? Let’s have a closer look at this technology and check how it works.

What Are Blockchain Rollups?

Blockchain rollups are Layer 2 solutions that improve blockchain scalability. They combine multiple transactions on a Layer 2 blockchain and turn them into a single piece of data. This data is then sent back to the main Layer 1 blockchain. By processing transactions off-chain and submitting the results as one, rollups help reduce congestion on the mainnet.

Why Are Rollups Needed?

Blockchains store limited data in each block. When demand increases, the network slows, and transaction costs rise. The mainnet prioritizes transactions with higher fees, leaving others waiting. As user activity grows, this problem worsens, making networks slower and more expensive.

How Do Rollups Help?

Rollups process transactions off-chain and send only summary data to the mainnet. This reduces the mainnet’s workload and lets a single data block contain many transactions. As a result, networks process more transactions faster and at lower costs.

Types of Rollups

Rollups come in two main types, each with unique features and security models.

ZK Rollups

ZK (Zero-Knowledge) rollups bundle transactions, verify them off-chain, and submit proofs to the mainnet. They ensure security and efficiency by generating "validity proofs."

• ZK-SNARKs
  ZK-SNARKs (Succinct Non-Interactive Argument of Knowledge) provide small, fast, and secure proofs. They use advanced cryptography to ensure transactions are valid without revealing extra details. These are efficient but rely on trusted setups and are vulnerable to quantum computing attacks.
• ZK-STARKs
  ZK-STARKs (Scalable Transparent Argument of Knowledge) improve on ZK-SNARKs by being more transparent and scalable. They don’t require trusted setups, making them more secure. However, their proofs are larger and take more time to verify.

Optimistic Rollups

Optimistic rollups assume all transactions are valid by default. They process transactions off-chain and submit compressed data to the mainnet. If a transaction is challenged, the system uses fraud proofs to verify its legitimacy.

Optimistic rollups are simpler and cheaper to implement than ZK rollups. However, they rely on a challenge system, which can delay transaction finality.

Comparing ZK and Optimistic Rollups

ZK rollups provide faster finality and stronger security but require advanced hardware and are costly. Optimistic rollups are easier and cheaper to deploy but have higher fraud risks without honest validators. Both play key roles in scaling blockchains.

Blockchain Rollups: A Scalable Future

Blockchain rollups are crucial solutions for improving Ethereum’s scalability. They tackle the problem in different ways, balancing security and efficiency based on their design.

This technology is still new, so its full potential remains to be seen. However, rollups and similar innovations show that blockchain is still evolving. With strong efforts to make blockchains more efficient and scalable, their uses are likely to grow in the future.