Federated learning
Federated learning trains a shared model across many devices without any individual device's raw data ever leaving that device, sharing only model updates instead.
Prerequisite: Differential privacy
What matters
Because raw personal data never has to be centralized, federated learning can reduce privacy risk while still allowing a useful shared model to be trained across many users.
Example
A keyboard app might improve its predictive text model by learning from typing patterns on each phone locally, sending only aggregated model updates back, never the actual typed text.
Common misconception
Federated learning does not automatically guarantee complete privacy; the shared model updates themselves can sometimes still leak information about the underlying data.
Recall question
What does federated learning share between devices, instead of raw personal data?