What is the relationship between TensorFlow and Keras?

TensorFlow is an open-source library for building and training deep learning models, while Keras is a high-level neural network API that can run on backends like TensorFlow. Keras is considered a more user-friendly and intuitive interface for TensorFlow, making the design and training of deep learning models simpler. In fact, the TensorFlow team integrated Keras into TensorFlow in 2017, making Keras the default high-level API for TensorFlow users to build their models. Keras itself can also run on other deep learning frameworks such as Microsoft Cognitive Toolkit (CNTK) and Theano.