This document introduces ML.NET, an open-source machine learning framework for building custom machine learning models. It discusses why machine learning is important, with examples like personalized recommendations and data mining. Key applications of ML.NET are mentioned, such as sentiment analysis, product recommendation, and fraud detection. The document also provides an overview of machine learning techniques like clustering, regression, and classification and the four stages of building models with ML.NET: initializing the model, training it, scoring, and evaluating.