A Layer 1 blockchain is the base network that maintains its own ledger and consensus rules. Bitcoin and Ethereum are Layer 1 networks: they validate transactions, decide which history is authoritative and provide the settlement layer on which other systems can build.
The label is useful only when it explains architecture. It does not mean that every Layer 1 is equally decentralized, secure or scalable, and it should not be confused with a ranking. A fast network can depend on demanding hardware or concentrated validators; a slower one may prioritize easier independent verification.
What a Layer 1 actually does
A base blockchain normally performs four related jobs:
- defines which transactions are valid;
- orders those transactions into a shared history;
- uses consensus to resolve competing views of that history;
- stores enough state or transaction data for participants to verify the result.
Some Layer 1 networks also provide a general execution environment for smart contracts. Others deliberately support a narrower set of operations. Bitcoin’s design focuses on transferring and securing bitcoin through proof of work and a constrained scripting system. Ethereum uses proof of stake and a programmable execution layer that supports contracts and decentralized applications.
Those are different designs, not different levels of the same product.
Consensus, execution and data availability
Discussions about Layer 1 often compress several functions into the word “blockchain.” Separating them produces a clearer comparison.
Consensus determines how the network agrees on an ordered history. Bitcoin miners compete through proof of work, and confidence increases as additional work is built on top of a block. Ethereum validators stake ETH, propose blocks and attest to checkpoints under proof-of-stake rules. Ethereum completed that transition in The Merge on September 15, 2022; our updated guide explains what happened to Ethereum 2.0.
Execution applies transactions to the current state. On a smart-contract network, this includes running contract code and updating balances or storage. Data availability concerns whether participants can obtain the information needed to verify the resulting state. A network can improve one dimension while creating pressure elsewhere.
Why Layer 1 blockchains face scaling trade-offs
Every validating node must be able to keep up with the chain’s rules and data. Increasing block capacity or reducing block time may raise throughput, but it can also increase bandwidth, storage and hardware requirements. If fewer people can operate independent nodes, practical verification may become more concentrated.
This tension is often summarized as a trade-off among decentralization, security and scalability. It is not a mathematical law that assigns every network one fixed position. Protocol design, client diversity, validator economics and hardware change over time, so comparisons should name the metric and the date.
Transaction-per-second claims are particularly easy to misuse. Advertised capacity may describe a laboratory test, a simple transfer workload or an execution ceiling rather than sustained application throughput. Finality, failed transactions, data storage and the hardware needed to reproduce the result matter as much as the headline number.
What is Layer 2?
A Layer 2 processes activity outside the base chain while using the Layer 1 for important security or settlement functions. On Ethereum, optimistic and zero-knowledge rollups execute transactions away from Mainnet and publish data or proofs back to it. Ethereum’s current scaling roadmap is centered on rollups and cheaper data availability.
That definition does not cover every network connected by a bridge. A sidechain can have its own validator set and security model, which means users depend on more than the Layer 1’s consensus. Marketing material may call almost any auxiliary chain “Layer 2,” so the practical questions are:
- who orders its transactions;
- where transaction data is published;
- how an invalid state can be challenged;
- who controls upgrades and emergency actions;
- how users can exit if the operator stops cooperating.
Layer 2 systems can reduce fees and increase capacity, but they may retain centralized sequencers, privileged bridges or upgrade keys. Deriving some security from a base chain does not eliminate those additional dependencies.
Examples without the market-cap ranking
Market capitalization changes continuously and says little about architecture. A more durable comparison looks at what each network asks participants to trust.
Bitcoin uses proof of work, a capped monetary policy and probabilistic settlement. Rewriting recent history requires competing with the accumulated work of honest miners. The Bitcoin developer guide explains how nodes validate blocks and select the chain with the most cumulative proof of work. Smaller proof-of-work chains may be more exposed when compatible hash power can be rented; see our guide to 51% attacks.
Ethereum now separates an execution layer from proof-of-stake consensus while remaining one Layer 1 network. Its scaling strategy gives rollups a larger role in user activity and uses Mainnet as a settlement and data layer. Other Layer 1s make different choices around validator hardware, parallel execution, governance and finality.
How to evaluate a Layer 1
Begin with verifiability rather than speed. Count independent validators or miners, but also examine operator concentration, client diversity and the cost of running a validating node. Determine whether finality is probabilistic or protocol-defined and what conditions could reverse it.
For programmable networks, inspect the execution environment, fee market, upgrade process and the parties able to pause or change core components. For users moving assets through bridges or Layer 2s, include those contracts and operators in the trust model.
A Layer 1 is the foundation of a blockchain ecosystem, not a promise that everything built above it inherits the same guarantees. The most useful analysis follows a transaction from execution to data publication and final settlement, identifying who could interrupt or alter it at each step.
Editorial note: This guide was substantially reviewed and rewritten on September 3, 2026 to reflect Ethereum’s proof-of-stake transition and its rollup-centric scaling roadmap. It is educational content, not investment advice.
