Ecommerce is one of the most successful businesses based on the Internet and machine learning plays a crucial role in making the experience personalized to the customer. But what does it take to make impact with machine learning? In this talk I give an outline of a typical ecommerce company and places where you could use machine learning, discuss how to connect business problems to machine learning problems. For some established cases, it is already clear how that link is made, but for many potential use cases, one first has to translate customer problems into machine learning problems. The resulting systems are often a hybrid of machine learning and more classical engineering. Finally, I’ll discuss different ways of how to structure the work of data scientists and engineers.