Federated learning is a machine learning approach that enables multiple devices or systems to train a shared model collaboratively without exchanging raw data. Instead, each participant trains the model locally on its data and sends only the model updates back to a central coordinator. This decentralized approach preserves data privacy and reduces bandwidth usage, making it ideal for scenarios where data privacy, security, or data locality are concerns. Federated learning comes in several forms, including horizontal federated learning, vertical federated learning, and federated transfer learning, each suited to different data distribution scenarios. The process involves initializing a global model, local client training, sharing updates, server aggregation, and model redistribution. Federated learning offers major benefits such as data privacy, reduced bandwidth costs, compliance with data residency laws, and enhanced personalization, but also presents challenges like data heterogeneity, client variability, communication overhead, and potential privacy risks from shared model updates. Implementing federated learning requires a structured approach, including defining participants, setting up infrastructure, selecting aggregation strategies, and securing the process.