---
type: "Concept"
title: "Cross-device vs cross-silo"
description: "Large fleets of weak devices vs a few institutions with legal separation."
tags: [fl, taxonomy, federated]
generated: { by: human:crpage, at: 2026-07-09T09:44:00Z }
status: stable
---

The primary FL axis. **Cross-device**: large fleets of weak/intermittent devices (phones), optimising for scale, bandwidth and participation. **Cross-silo**: a small number of institutions (hospitals, councils), optimising for trust, governance, legal separation and coordination. UK public-sector federation is overwhelmingly cross-silo.

Relates to: [Federated learning](federated-learning.md), [MELLODDY](../research/melloddy.md).