Apache Flink is an open-source stream processing framework for distributed, high-performing, always-available, and accurate data streaming applications. It provides both stream and batch processing capabilities with low latency and high throughput.

Key features include:

• Event Time Processing: Handles out-of-order events and late data
• Stateful Computations: Maintains application state across events
• Fault Tolerance: Automatic recovery from failures with exactly-once processing semantics
• Low Latency: Sub-second processing latencies
• High Throughput: Can process millions of events per second

Flink is commonly used for real-time analytics, complex event processing, ETL operations, fraud detection, and building event-driven applications that require low-latency processing of continuous data streams.