Dask is an open-source library in Python designed for parallel computing. It allows users to scale their data processing tasks across multiple cores or even multiple machines, making it easier to handle large datasets that don't fit into memory. Dask provides familiar interfaces similar to Pandas and NumPy, enabling users to work with large arrays and dataframes seamlessly. Dask operates by breaking down complex computations into smaller, manageable tasks that can be executed concurrently. This approach not only speeds up processing times but also optimizes resource usage. It is particularly useful in data science and machine learning applications, where large-scale data manipulation is common.