Blockchain Trilemma
The widely-discussed challenge that a blockchain design tends to optimize for at most two of decentralization, security, and scalability at once.
The blockchain trilemma (also called the scalability trilemma) describes the widely-discussed challenge that a blockchain's design tends to optimize for, at most, two of three properties simultaneously — decentralization, security, and scalability — with gains in one commonly coming at some cost to another.
It's a useful lens for comparing different blockchain designs' trade-offs, though it's a framework, not a mathematical law — some designs (Layer 2 scaling, in particular) aim to work around the trilemma rather than simply accepting it. See Kaavon's "Understanding the Blockchain Scalability Trilemma" guide for how specific designs navigate this trade-off.
Examples
- A highly decentralized, highly secure base-layer blockchain that processes transactions slowly is commonly discussed as an example of prioritizing two sides of the trilemma over the third.
- Layer 2 scaling solutions are commonly framed as an attempt to improve scalability without directly sacrificing the base layer's decentralization or security.