Spark Structured Streaming is Apache Spark's API for processing continuous streams of data in real-time. It treats data streams as unbounded tables, allowing you to write SQL or DataFrame queries that run continuously. Structured Streaming handles complexities like late-arriving data, stateful processing, and fault tolerance. Applications include real-time analytics dashboards, anomaly detection, data pipelines, and event-driven systems. Spark Structured Streaming is the foundation for real-time data platforms.