Apache Flink is a system designed for efficient, distributed, high-speed stream processing. It offers robust event-time support, exactly-once semantics, and the ability to handle large amounts of data. Flink's differentiation is its robustness in fault-tolerance and latency, along with its powerful stream-batch unification which makes it possible to run batch processing as a special case of stream processing. This makes Flink versatile in a wide range of use cases, from real-time analytics to machine learning, and in environments from business applications to big data analytics. Its flexible windowing and rich function APIs let developers customize and optimize their data processing pipelines, leading to faster insights and decision making.