Blockchain trilemma

The trilemma describes the tension between three edges. Decentralization measures how many independent nodes can validate, which gives censorship resistance but limits the hardware that can be required and, with it, throughput. Security measures the ability to resist attacks, such as the cost of a 51% attack, and depends on the economic value the network secures and on the number and distribution of validators. Scalability measures transactions per second and cost per transaction. Raising hardware requirements or reducing validator count scales the network but centralizes it.

The trilemma is the framework that explains why Layer 2 (L2) networks and modular scaling exist. Rather than sacrificing decentralization or security on the base layer (L1), execution is delegated to a higher layer that inherits L1 security by publishing data or proofs on it. It also explains differing design philosophies: high-throughput chains that accept more centralization versus chains that prioritize decentralization and scale through rollups.

Ethereum prioritizes decentralization and security, and scales with rollups like Arbitrum, Optimism and Base. Solana prioritizes high throughput with more demanding hardware requirements. Modular architectures such as Celestia separate data availability from execution to tackle the trilemma layer by layer.