The article discusses the internals of PyTorch, a popular machine learning library, and provides an overview of its conceptual structure and implementation details. It covers topics such as tensor data types, strides, and views, as well as the library's extension points and automatic differentiation capabilities. The article is based on a talk given at the PyTorch NYC meetup in 2019 and provides a detailed explanation of the library's inner workings. The author aims to provide a map for contributors to navigate the PyTorch codebase and understand its underlying mechanics.