To learn more about cutting-edge data science tools like Apache Kafka, check out the Strata Data Conference in San Jose, March 5-8, 2018--registration is now open. Machine learning has become mainstream, and suddenly businesses everywhere are looking to build systems that use it to optimize aspects of their product, processes or customer experience. The cartoon version of machine learning sounds quite easy: you feed in training data made up of examples of good and bad outcomes, and the computer automatically learns from these and spits out a model that can make similar predictions on new data not seen before. What could be easier, right? Those with real experience building and deploying production systems built around machine learning know that, in fact, these systems are shockingly hard to build. This difficulty is not, for the most part, the algorithmic or mathematical complexities of machine learning algorithms. Creating such algorithms is difficult, to be sure, but the algorithm creation process is mostly done by academic researchers.