Introduction
摘要
This chapter introduces federated learning (FL), a distributed machine learning approach designed to address data privacy, security, and processing challenges in the era of big data and AI. FL allows model training across multiple devices or organizations without sharing raw data, thus enhancing privacy by only exchanging model updates. The chapter covers three FL modes: Horizontal Federated Learning (HFL), Vertical Federated Learning (VFL), and Transfer Federated Learning (TFL). It also explores recommender systems (RecSys), focusing on traditional methods like collaborative filtering and advanced techniques, such as graph-based approaches. Finally, the chapter discusses Federated Recommender Systems (FedRec), which integrate FL and recommender systems to improve privacy-preserving recommendation services while addressing challenges like data heterogeneity and communication overhead.