A recommendation engine is a software system that analyzes large amounts of transactional data and distills personal profiles to present its users with relevant products/information/content. We see them in a wide variety of domains and applications and they help us navigate the overwhelming choice that we face everyday. This tutorial will formally introduce the concepts and definitions of the recommendation systems literature and will quickly move on to an iterative process for building a minimal reco engine. In the process, we'll learn about the building blocks for scientific computing in Python: NumPy and (more recently) pandas.