Jeff Bezos (pictured), who founded Amazon and turned the book e-tailer into a retail colossus, has stepped down as CEO of the company.

He will become executive chairman of the company’s board.

He will be replaced by Andy Jassy, currently chief of the company’s Amazon Web Services cloud computing unit.

While estimates vary, Amazon is said to account for about 23% of the dollars spent online in the U.S., according to an analysis by Digital Commerce 360.

In an email to his employees, Bezos said, “Being the CEO of Amazon is a deep responsibility, and it’s consuming. When you have a responsibility like that, it’s hard to put attention on anything else.”

Bezos, who is now ranked among the richest people in the world, now plans to focus on other projects.

Amazon started as a bookseller, but gradually expanded into other markets. The store was often hailed for its customer focus, though competitors and many of its vendors have complained about its hard-nosed and often predatory tactics.

According to the book The Everything Store, in 2003, Bezos set his sights on jewelry; it was tempting to the Amazon owner because it was a high-margin, small-value product, which meant low shipping costs. He developed a build-your-own-ring tool, and wanted to develop a box as “iconic as Tiffany’s.”

Yet he also advised his sellers to “ignore the conventions of pricing in the jewelry business.”

“Amazon had to concern itself only with what was best for the customer,” the book said. “[Bezos] envisioned customers buying a bracelet on the site for $1,200 and then going to get an appraisal and finding out from the local jeweler that the item was actually worth $2,000.”

He eventually gave up his focus on jewelry, though the company’s sheer size had made it a considerable player in the market.

(Photo courtesy of Amazon)