This document discusses deep learning and DL4J. It begins with an overview of deep learning, describing it as automated feature engineering through chained techniques like restricted Boltzmann machines. It then introduces DL4J, describing it as an enterprise-grade Java implementation of deep learning that supports parallelization on Hadoop, Spark, and GPUs. The rest of the document discusses building deep learning workflows with DL4J and related tools like Canova and Arbiter, providing an example of vectorizing and modeling iris data from a CSV file on the command line.