Layer 2 (L2)

Key points

• Layer 2, or second layer, is a protocol built on top of a main blockchain to process transactions off it and increase capacity.
• By moving processing off the base layer, it reduces the cost per transaction and the waiting time, while keeping the security inherited from the main network.
• It is one of the main responses to the scaling problem of the busiest blockchains, making frequent, low-value payments viable.

What is a layer 2?

Layer 2 is an additional layer that runs on top of an existing blockchain, called the base layer or layer 1. Instead of recording every operation directly on the main network, which has limited capacity, the second layer groups and processes transactions separately and periodically settles a summary on the base layer. This way, it gains speed and cost savings without giving up the security of the network that underpins it.

How it works

The core idea is to execute the bulk of transactions off the base layer and use the main network only as an anchor for security and final settlement. Different designs do this in distinct ways. Some process transactions in batches and publish a summary on the base layer with proof that everything is valid. Others use channels between participants that only record the final result on the main network.

In all cases, the second layer seeks to inherit the security of the base layer: even though the operation happens off it, it is possible to fall back on the main network to guarantee that no one was harmed. This makes it possible to reduce fees and increase speed without creating a fully separate, less secure network.

The practical result is a much lower cost per transaction, which makes small, frequent payments viable that would be too expensive on the base layer.

Why it matters

For payments, the scale and low cost of a second layer are decisive: settling small amounts requires minimal fees. Companies that process many transactions benefit from layers that reduce the unit cost, while retaining the ability to fall back on the main network as a security guarantee. Payment corridors that need cheap, fast settlement find in these layers a way to scale without migrating to a less secure network.

Risks and limitations

Each design has its own trade-offs: some rely on the honesty of operators for a period, others on challenge mechanisms with deadlines. Moving funds between layers can involve waiting periods and the use of bridges, which have already been targets of attacks. Effective security depends on the solution truly anchoring its guarantees on the base layer.