Team Topologies
A model of four team types and three interaction modes used to design an organisation deliberately for a target architecture and flow of change.
The four types: stream-aligned — owns a slice of business value end to end, and should be the large majority of teams. Platform — provides internal services that reduce cognitive load for stream-aligned teams, treated as a product with users rather than as a gatekeeper. Enabling — helps other teams acquire capability, then leaves. Complicated subsystem — owns something requiring specialist knowledge, and exists only where that specialism is genuinely rare.
The three interaction modes: collaboration (high bandwidth, temporary, for discovering an interface), X-as-a-service (low bandwidth, stable, the normal steady state), and facilitating (one team helping another improve).
The concept that does most of the work is cognitive load: a team's ownership must fit within what it can hold. Most platform investment is justified by this — not by reuse, but by reducing the amount each stream-aligned team must understand to ship safely.
Two failure modes it names precisely: collaboration that never ends, which should have converged into a service interface and instead becomes permanent coupling; and a platform that behaves as a gatekeeper, which reintroduces the queue the structure was meant to remove.