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Vol. 1 · Ed. 2026
CyberGlossary
Entry № 410

Federated Learning

What is Federated Learning?

Federated LearningA distributed machine-learning paradigm in which many clients collaboratively train a model under a central coordinator while keeping their raw data on-device.


Federated Learning (FL) trains a shared machine-learning model across many participants — phones, hospitals, banks — without centralizing the training data. Each client computes a local gradient or model update on its own data and uploads only the update to an aggregator, which combines them (often via FedAvg) into a new global model. Because raw updates can still leak information about training data, modern deployments layer in cryptographic protections: secure aggregation, differential privacy, and sometimes homomorphic encryption or MPC. Google introduced FL for Gboard keyboard suggestions in 2017, and it is now widely used for healthcare imaging, fraud detection across institutions, and on-device personalization of LLMs.

Examples

  1. 01

    Gboard learns next-word predictions from millions of phones without sending typed text to Google's servers.

  2. 02

    Hospital consortia jointly train diagnostic models on patient data that never leaves each institution.

Frequently asked questions

What is Federated Learning?

A distributed machine-learning paradigm in which many clients collaboratively train a model under a central coordinator while keeping their raw data on-device. It belongs to the Cryptography category of cybersecurity.

What does Federated Learning mean?

A distributed machine-learning paradigm in which many clients collaboratively train a model under a central coordinator while keeping their raw data on-device.

How does Federated Learning work?

Federated Learning (FL) trains a shared machine-learning model across many participants — phones, hospitals, banks — without centralizing the training data. Each client computes a local gradient or model update on its own data and uploads only the update to an aggregator, which combines them (often via FedAvg) into a new global model. Because raw updates can still leak information about training data, modern deployments layer in cryptographic protections: secure aggregation, differential privacy, and sometimes homomorphic encryption or MPC. Google introduced FL for Gboard keyboard suggestions in 2017, and it is now widely used for healthcare imaging, fraud detection across institutions, and on-device personalization of LLMs.

How do you defend against Federated Learning?

Defences for Federated Learning typically combine technical controls and operational practices, as detailed in the full definition above.

What are other names for Federated Learning?

Common alternative names include: FL, Federated machine learning.

Related terms