Machine Learning for Recommender Systems: A Beginner's Guide

How does Amazon recommend products you might be interested in purchasing? OR How does Netflix decide which movies or TV shows you might want to watch? OR How does Facebook or LinkedIn decide who might you want to form a link with? OR How does Udemy decide what courses to market to you? OR How does New York Times decide which news you might be interested in reading? How does Amazon recommend products you might be interested in purchasing?