What is Layer 2?
A layer 2 is a network built on top of a layer 1 that processes transactions cheaper and faster, then posts compressed data or proofs back to the base chain so it inherits the layer 1's security.
Also known as: L2 · rollup · scaling solution
In plain terms
Layer 2s exist because base blockchains get congested. Instead of every transaction competing on the main chain, a layer 2 batches thousands of them and publishes one compressed summary to the layer 1.
The user experience feels like a faster, cheaper version of the same blockchain, with the base chain as the final referee.
How it works
A layer 2 executes transactions on its own chain and periodically commits the results to the layer 1, either as raw transaction data (optimistic rollups) or as cryptographic validity proofs (zk rollups).
Because the layer 1 stores the data or verifies the proofs, users can exit to the base chain even if the layer 2's operators disappear — a property called data availability.
Tokens issued under Ethereum standards work on its layer 2s with minimal changes, which is why much DeFi and stablecoin activity has migrated there.
Example
Hypothetical: an exchange moves settlement of its stablecoin transfers to an Ethereum layer 2. Users pay cents instead of several dollars per transfer, withdrawals to Ethereum mainnet still work normally, and the base chain guarantees the records are real.
Why it matters for founders and investors
Layer 2s change the economics of on-chain products: fees low enough for retail payments, frequent small distributions and high-frequency flows become practical.
They also add a dependency: the layer 2's own operators, sequencer and exit mechanisms are additional trust assumptions the user should understand.
Common misconceptions
Layer 2s are not independent blockchains with their own security. Their guarantees come from the layer 1, and the details of how each rollup posts data and handles exits vary and matter.
Frequently asked questions
What is the difference between optimistic and zk rollups?
Optimistic rollups assume transactions are valid and allow a challenge window during which fraud can be proven; zk rollups publish a cryptographic proof that the batch is valid. Optimistic designs are simpler and older; zk proofs offer faster finality.
Do I pay gas fees on a layer 2?
Yes, but they are typically far lower than on the base chain. Moving assets between the layer 1 and the layer 2 (bridging) usually costs mainnet-level fees.