Full article originally appeared in Entrepreneur magazine

Jeff Bezos recently briefly overtook Bill Gates to become the richest man in America. It’s a reminder, much like Amazon’s most recent $13.7-billion acquisition of Whole Foods, of the remarkable power of the company that Bezos has created and the straightforward strategy he used to create his empire. Now, with each new click and each new transaction, Amazon grows its war chest of consumer and market data and the company’s growth appears — at least for the moment –unstoppable.

But it was not always so. Once upon a time, Amazon sold only books. Bezos’s initial focus on books constitutes the greatest execution of a beachhead marketing strategy ever. By creating a narrow and winnable focus for his first product, Bezos was able to build the fundamentals of his company, and create a launching pad for Amazon to grow into different markets over time.

Today, when I want to buy audiobooks, gardening tools or a Spike Lee Brooklyn bicycle cap, I shop through Amazon and know it will all be delivered, courtesy of Amazon Prime, to my front door in Boston in two days. I have come to depend on Amazon’s recommendations and customer feedback to guide my purchases. I now have an Amazon TV system and have installed Alexa systems at both home and at work. My publisher directs me to the Amazon author section to see how many copies of my book have been sold each week, and in what regions. And when I relax at the end of the day, I read the Washington Post on my iPad, which is free with Amazon Prime. And it all started with books.