Layer 2 networks explained
What a layer 2 network is
Layer 2 crypto refers to networks built on top of a base blockchain, called layer 1, that process transactions off the main chain to reduce load and cost. A layer 2 still relies on the layer 1 chain to settle or resolve disputes, which is why it is described as a layer on top rather than a fully separate blockchain.
How rollups and the Lightning Network cut fees
On Ethereum, the main layer 2 design is the rollup. A rollup executes many transactions off the main chain, then posts the batch data, or a proof that the batch is valid, back to Ethereum. The cost of that posting is shared by everyone in the batch, so each transaction costs less. Rollups come in two main types, optimistic and zero-knowledge, which differ in how they show that batches are valid.
On bitcoin, the best-known layer 2 is the Lightning Network. Users open payment channels, record balances between themselves off chain, and settle only the opening and closing transactions on the bitcoin blockchain. This makes small, fast payments cheap, but funds must be locked in channels, and you need a wallet that supports the network. For the base-chain side, see bitcoin transaction fees.
Moving funds between layers and what to check
Moving coins onto and off a layer 2 usually requires a bridge or an exchange withdrawal that supports that network. Withdrawals from some optimistic rollups can take days, because a challenge period allows a batch to be disputed before it is final. Costs on the base chain also change with demand, as explained in ethereum gas fees.
Layer 2 networks are newer, and their software and operators can carry extra risks, including bugs and reliance on a sequencer, the operator that orders transactions. Crypto prices are volatile, and you can lose money when using any network.
Frequently asked questions
Are layer 2 networks as secure as the base chain?
They inherit some security from the base chain, because final settlement or dispute resolution happens there, but they add their own software and operator risks. Security depends on each network's design, maturity and audits. A layer 2 can be reasonable to use and still be less secure than the base chain, so research each network separately.
Do I need a different wallet for a layer 2 network?
Often you need a wallet that supports the layer 2 network, and you need the coin used to pay its network fees. Addresses on many networks look alike, which makes sending to the wrong network a real risk. Confirm the network name before every transfer.