There are few U.S. companies that have dominated their industry like Amazon. The e-commerce giant continues to be among the hottest topics in business, while CEO Jeff Bezos is the richest person on Earth, worth in excess of $130 billion.

In 2018, Amazon posted a record $10.1 billion in net income. Its growth has also been staggering, having posted only a $3 billion profit in 2017, and barely any in 2016. With all this growth, the actual source of Amazon’s immense profit may come as a surprise to some.

Despite the company’s dominance om e-commerce, that segment does not account for most of Amazon’s business. In fact, according to CNBC, Amazon Web Services (AWS), its cloud computing platform, is the main profit driver for the company. Comprised of a massive bank of servers, AWS provides processing power and storage for companies, individuals, and government agencies. In 2018, AWS alone posted revenue of $25.7 billion, greater than the likes McDonald’s and Macy’s. Investment in this service has effectively turned Amazon into a technology company, as well as an e-commerce outfit.

Advertising is also an increasingly important sector of Amazon’s business, due to its position as the center of the retail world. Some analysts have predicted that at its current rate of growth, Amazon’s advertising arm could eclipse AWS by 2021. In 2018, it sold $10.1 billion in advertising.

The company’s dealings with third-party sellers who operate through Amazon’s store are also generating more and more profit, with higher margins. By 2018, over half of the items sold on Amazon were from third parties.

Yet, there is uncertainty about Amazon's future.

While reiterating a "buy" rating in May, analyst Tom Forte of D.A. Davidson wrote that four warning signs — the law of large numbers, succession plans, competition and regulation —could mean the "demise of Amazon."

Amazon also lags in international sales, having posted losses in each of the last 3 years. It lost $2.1 billion on $65.8 billion in international sales in 2018 — a sharp contrast to making $7.2 billion on $141.3 billion in North American sales.

Sen. Elizabeth Warren of Massachusetts, a top contender of the Democratic nomination in 2020, has even proposed breaking up tech giants like Amazon. 

Jeff Bezos Amazon CEO Jeff Bezos attends the Amazon Prime Video's Golden Globe Awards After Party at The Beverly Hilton Hotel on Jan. 6, 2019 in Beverly Hills, California. Photo: Emma McIntyre/Getty Images