PyTorch is an open source machine learning library that specializes in tensor computations, automatic differentiation, and GPU acceleration. For those reasons, PyTorch is one of the most popular deep learning libraries, competing with both Keras and TensorFlow for the prize of “most used” deep learning package:
PyTorch tends to be especially popular among the research community due to its Pythonic nature and ease of extendability (i.e., implementing custom layer types, network architectures, etc.).