Change Data Capture (CDC) is a design pattern that tracks and streams every change (insert, update, delete) made to a dataset in near real-time. Originally developed for database replication, CDC has evolved into the backbone of modern event-driven architectures, enabling real-time analytics, microservices synchronization, and data lake ingestion without impacting source system performance. Unlike batch ETL which periodically polls tables, CDC reads transaction logs—the append-only journal every ACID database maintains—and converts those low-level log events into structured change streams. This log-based approach delivers sub-second latency at a fraction of the resource cost, making CDC the de facto standard for keeping analytical and operational systems in sync.