Scikit-learn is an open-source machine learning library for the Python programming language. It provides simple and efficient tools for data analysis and modeling, making it accessible for both beginners and experienced users. The library supports various supervised and unsupervised learning algorithms, including classification, regression, and clustering. Designed to work seamlessly with other scientific libraries like NumPy and Pandas, Scikit-learn emphasizes ease of use and flexibility. It includes features for model selection, evaluation, and preprocessing, allowing users to build and optimize machine learning models effectively.