Amazon workers have held an increased number of protests over the last year, which is one sign that momentum to organize has picked up among some of its 650,000 worldwide employees. But unionizing efforts so far have not succeeded. Amazon increased minimum wage to $15 an hour last year and offers generous benefits. It's also fending off unions using tweets, training videos and internal hires. Watch the video to learn what unions are all about and how they could impact Amazon and its workers.