For the remainder of the book, we will be using Keras and TensorFlow. Most of the examples we will be exploring require a GPU for acceleration. Most modern deep learning frameworks, including TensorFlow, use GPUs to greatly accelerate the vast amount of calculations required during network training. Without a GPU, the training time of most of the models we discuss will be unreasonably long.

If you don't have a computer with a GPU installed, GPU-based compute instances can be rented by the second from a variety of cloud providers including Amazon's Amazon Web Services and Google's Google Cloud Platform. For the examples in this book, we will be using a p2.xlarge instance in Amazon EC2 running Ubuntu Server 16.04.  The p2.xlarge instance provides an Nvidia Tesla K80 GPU with 2,496 CUDA cores, which will make running the models we show in this book much faster than what is achievable on even very high end desktop computers.