PyTorch is a popular open-source deep learning framework that provides a flexible and dynamic computational graph. It offers a wide range of functionalities for building and training neural networks, including automatic differentiation with Autograd, a Neural Networks Module for defining network architectures, and DataLoader and Dataset classes for efficient data loading and preprocessing. With support for GPU acceleration and a rich ecosystem of libraries like TorchVision and TorchText, PyTorch is a powerful tool for deep learning research and production.