What is Layer 2?

A layer 2 is a network that processes transactions on its own and settles the results on a base chain, layer 1, inheriting that chain’s security while charging a fraction of its fees. On Ethereum the layer 2s that matter, Arbitrum, Optimism, Base, zkSync Era, Linea, Scroll, Mantle and Blast among them, are rollups: they execute transactions off the main chain, compress them, and post the compressed data back to Ethereum where it is final.

From a wallet’s point of view the most useful property is that an Ethereum address is also an address on every EVM layer 2. The same private key, the same 0x string, works on all of them, and a wallet accumulates balances across them almost without noticing: bridged ETH here, an airdrop there, a lending position that stayed. Bridging is how assets move between the layers, and a bridge is a transfer between your own addresses, not a sale.

The differences are in the details. Optimistic rollups such as Arbitrum and Optimism assume transactions are valid and allow a challenge window; zero-knowledge rollups such as zkSync Era, Linea and Scroll prove validity mathematically. Some layer 2s use their own gas token, Mantle with MNT for example, and one, Blast, rebases ETH and stablecoin balances so they grow on their own.

TrueHold reads every EVM layer 2 it supports from the single 0x address you paste, gives each its own slice inside one portfolio, and treats bridges as the transfers they are. Each supported layer 2 has a coverage page on this site.

The practical rule for a portfolio is to count every layer 2 a wallet has touched, because balances migrate there quietly and stay. A tracker that only reads Ethereum mainnet is showing a fraction of what an active address actually holds.

Each one is also a separate gas balance to keep topped up, which is the small tax of living across several layers.