Layer 1 and Layer 2 Blockchains

The question of how to scale blockchains - how to process more transactions faster and cheaper without sacrificing security or decentralisation - is the central technical challenge of the entire industry. Bitcoin processes approximately 7 transactions per second. Ethereum processes approximately 15-30. Visa processes approximately 24,000. For blockchain technology to support global-scale use cases, this gap must be addressed. Layer 1 and Layer 2 solutions represent two fundamentally different approaches to this challenge - and understanding the distinction explains much of the competitive landscape among crypto projects.

The Scalability Problem

Why can't blockchains simply process more transactions? Because the properties that make them secure - decentralisation and the requirement that every node processes every transaction - create inherent throughput limits. Every node on the Bitcoin network processes and stores every transaction in Bitcoin's history. If Bitcoin processed 24,000 transactions per second like Visa, the data requirements for running a full node would be enormous - effectively excluding ordinary computers and centralising the network to only institutional-grade hardware.

This creates the Scalability Trilemma: blockchains can generally achieve two of three properties - decentralisation, security, and scalability - but not all three simultaneously. Bitcoin maximises decentralisation and security at the cost of scalability. High-throughput Layer 1s like Solana sacrifice some decentralisation for speed.

What Is Layer 1?

Layer 1 (L1) is the base blockchain - the foundational network that processes and records transactions directly, maintains consensus, and provides the security guarantees on which everything else builds. The rules of the Layer 1 - how transactions are validated, how consensus is achieved, how new tokens are created - are fundamental and difficult to change.

The Major Layer 1 Blockchains

What Is Layer 2?

Layer 2 (L2) solutions take a different approach to scaling: rather than replacing the base blockchain, they build on top of it. Transactions are processed off the main chain - faster and cheaper - and the final state is periodically submitted to the Layer 1, which provides the ultimate security guarantee. Users benefit from L2 speed and cost while inheriting L1 security.

This is the approach Ethereum has chosen as its primary scaling strategy: rather than making the base layer faster (which would compromise decentralisation), Layer 2 networks handle the volume while Ethereum provides the security anchor.

The Major Layer 2 Solutions

The two main rollup types differ in how they prove transaction validity. Optimistic rollups assume transactions are valid and use a challenge period where fraud proofs can be submitted. ZK rollups use cryptographic proofs to mathematically verify validity immediately - stronger security but more computationally intensive.