Layer 2 is not an escape from Layer 1. It is an extension of its security model into higher throughput domains. The base chain remains the anchor -- immutable, slow, expensive, and trustworthy.

Rollups compress transaction data into cryptographic commitments. Optimistic rollups assume validity and wait for challenges. ZK-rollups prove validity before submission. Both inherit L1 security.

The topology of Layer 2 is not a hierarchy. It is a mesh -- networks of specialized chains, each optimized for a class of computation, all anchored to the same bedrock consensus.

Throughput is not the metric that matters. Finality is. The time between "transaction submitted" and "transaction irreversible" defines the user experience of trust.