How do Layer 2 solutions (rollups, state channels) reduce gas fees?

Rollups, whether optimistic or ZK-based, collect many transactions, execute them off-chain, and submit a single proof or batch summary to Layer 1; that means the expensive calldata and signature costs are shared instead of duplicated per user, sharply lowering per-tx gas. State channels take it further by letting a fixed set of participants exchange signed state updates directly, only touching the base layer when opening or closing the channel. Both models rely on deferring most execution off-chain while anchoring security to Ethereum, so you still get consensus guarantees with a much smaller gas bill for routine interactions.

Rollups bundle transactions off-chain, so each user pays one shared fee; state channels keep repeated trades off-chain.

Last summer I was trying to flip some NFTs during a crazy-busy drop. Mainnet gas was eating half my budget, so I bridged to Optimism. Yes, the bridge fee stung a little, but once I was there every swap or approval cost pennies because the rollup batches thousands of actions and only submits a compressed summary to Ethereum. I barely felt those transactions anymore, even when the mainnet was congested, I could mint and flip without refreshing my wallet. For friends who game together, we opened a state channel for our in-game trades. We funded it once on Ethereum, then did dozens of swaps inside the channel with zero extra gas. Only when we closed it did we pay another small on-chain fee. Between rollups cutting each action’s effective fee and state channels letting repeated back-and-forth happen off-chain, it was the only way I could keep using Ethereum without bleeding gas.