What is a Layer 2 blockchain?
What a Layer 2 is, how it makes transactions faster and cheaper on top of a blockchain and which kinds exist.
Read guideLayer 1 vs Layer 2
The evolution of blockchain networks has led to a central question in the development of this technology, namely how to increase processing capacity without compromising the security, decentralization, and utility that justified its emergence. In this context, the concepts of Layer 1 and Layer 2 have become particularly important. They describe different levels of blockchain infrastructure and help explain much of the current architecture of decentralized applications. Although both pursue objectives related to scalability, their mechanisms and responsibilities are different.
Comparison
| Criterion | Layer 1 | Layer 2 |
|---|---|---|
| What it is | The base blockchain | A system built on top of a Layer 1 |
| Role | Consensus, security and settlement | Faster, cheaper execution |
| Security | Its own | Partly relies on the Layer 1 |
| Fees | Higher during congestion | Usually lower |
| Examples | Bitcoin, Ethereum, Solana | Lightning Network, rollups |
Layer 1
A Layer 1, also known as a base layer, is the blockchain itself on which transactions are recorded and the network’s main state is established. Bitcoin, Ethereum, Solana, and Avalanche are examples of networks that can be considered Layer 1s, although their architectures and consensus mechanisms differ substantially. This layer constitutes the fundamental infrastructure on which digital assets, smart contracts, financial protocols, and other blockchain-based applications can be built.
The function of a Layer 1 goes far beyond storing transactions. The network must provide a mechanism for reaching consensus among participants who do not necessarily trust one another. It must also determine the system’s valid state, prevent double spending, and preserve the historical integrity of the ledger. To achieve this, it uses different architectures and consensus mechanisms. Bitcoin uses proof of work, while Ethereum uses proof of stake. Other networks have developed different mechanisms intended to alter the balance among security, decentralization, and processing capacity.
That balance is precisely one of the structural problems of many blockchains. A completely open network, with numerous independent participants and high security requirements, can have difficulty processing a very large volume of transactions while keeping costs low. When demand increases, users may compete for limited block space and fees may rise. The so-called blockchain trilemma summarizes this tension by pointing to the difficulty of maximizing decentralization, security, and scalability simultaneously without making architectural compromises.
Layer 2
Layer 2s emerge as one of the main responses to this problem. They are systems built on top of a base blockchain that allow certain operations to be processed outside the main layer and later move the information necessary to ensure security, verify results, or update the relevant state back to it. Instead of requiring every operation to be processed individually on Layer 1, part of the work can be carried out on a secondary infrastructure specifically designed to increase capacity.
One of the most important groups within this ecosystem consists of rollups. Their general principle is to execute transactions outside the base layer and subsequently group multiple operations into a reduced amount of data that is published to or verified on the underlying blockchain. This makes it possible to use some of the security of Layer 1 while reducing the amount of information that must be processed directly on it.
Within rollups, there are designs with different characteristics. Optimistic rollups initially assume that the grouped operations are valid and establish mechanisms to detect and challenge potentially incorrect operations. Zero-knowledge rollups use cryptographic proofs that make it possible to demonstrate the validity of a set of transactions without requiring Layer 1 to execute each of them individually again. Both approaches pursue a common goal—increasing throughput and reducing the cost per operation—although their technical mechanisms and operating models have important differences.
Another historical approach to Layer 2 is represented by payment-channel networks. Bitcoin Lightning Network is the best-known example. In this model, certain transactions can occur off the main chain, and only the information needed to open or close channels and resolve particular states is recorded on Bitcoin. The result is infrastructure designed to facilitate a large number of operations with much less interaction with the base blockchain.
How they share the work
The relationship between Layer 1 and Layer 2 can therefore be understood as a distribution of responsibilities. The former provides settlement infrastructure, consensus, and the system’s fundamental guarantees. The latter seeks to increase processing capacity and improve certain aspects of the user experience without requiring every operation to bear the same operating cost on the main chain. According to a common interpretation among specialists, Layer 2 does not replace Layer 1. Instead, it attempts to extend its capabilities through complementary architecture.
However, this separation also introduces new complexities. A Layer 2 needs mechanisms to communicate with Layer 1, move assets between the two layers, and ensure that operations executed on the secondary infrastructure can be correctly verified or finalized. Bridges and interoperability systems play a particularly important role here. Waiting periods, specific withdrawal mechanisms, or technical risks associated with the smart contracts and cryptographic systems used may also arise.
Decentralization and user experience
Decentralization is another important point of comparison. Not all Layer 1s have the same degree of decentralization, nor do all Layer 2s provide identical guarantees. A solution may initially depend on certain operators or sequencers responsible for ordering transactions. As these systems evolve, some projects seek to distribute these functions among a larger number of participants. Therefore, the Layer 2 label by itself does not determine the exact level of decentralization or security of a particular network.
The user experience also changes between the two levels. On a Layer 1, each operation interacts directly with the main blockchain and is subject to its capacity constraints and execution costs. On a Layer 2, the user may benefit from faster or cheaper transactions, but must understand that they are using additional infrastructure with its own mechanisms. In some cases, assets must also be transferred from Layer 1 to Layer 2 before certain applications can be used.
Economic impact and limits
From an economic perspective, Layer 2s are also changing the structure of blockchain ecosystems. Lower transaction costs can make applications viable that would be too expensive on a congested base layer. Blockchain-based games, certain decentralized financial applications, and micropayment systems are among the use cases that can benefit from higher-capacity infrastructure.
Nevertheless, Layer 2s do not eliminate the fundamental limits of blockchains. Some information must still be anchored to or depend on Layer 1 to obtain security and settlement guarantees. For this reason, scalability improvements generally involve redistributing work rather than completely eliminating costs. Final efficiency depends on factors such as protocol design, data compression, data availability, and the main network’s capacity to absorb updates generated by its secondary layers.
Technological competition is not limited to a single architecture either. Some Layer 1s attempt to increase capacity directly through changes in chain design, higher processing rates, or other scalability solutions. In parallel, different Layer 2s develop mechanisms intended to reduce costs, improve interoperability, and simplify the user experience. This process is producing an increasingly modular ecosystem in which a single blockchain can serve as a security layer for numerous specialized networks.
The difference between Layer 1 and Layer 2 ultimately reflects two complementary levels in the evolution of decentralized infrastructure. Layer 1 represents the base on which consensus is established and the main state is maintained. Layer 2 shifts part of the activity to systems built above it in order to improve scalability and reduce certain costs. Understanding this relationship is essential for analyzing how blockchain networks can grow without abandoning the properties that underpin their operation.
The future of this architecture will depend to a large extent on how the balance among security, decentralization, performance, and ease of use evolves. Layer 1s will continue to provide the fundamental guarantees on which their respective ecosystems depend, while Layer 2s may take on a growing share of everyday activity. Rather than suggesting a replacement of one layer by the other, the sector’s evolution points toward progressive integration in which each level performs different functions within an increasingly complex and specialized blockchain infrastructure.