Why A Company You've Never Heard of Is Expected to Have the Biggest IPO Ever

— -- intro: The largest initial public offering of a company ever, which is expected to happen this week through the New York Stock Exchange, will likely raise more than $24 billion. But many Americans have likely never used or even heard of the firm.

It's an Internet company, not surprisingly, and it's called Alibaba. The company has four main areas of revenue, according to Santosh Rao, head of research of Manhattan Venture Partners. And here's what they are:

Hong Kong Rethinks Rules After Alibaba IPO Loss

Manual Transmissions Getting Rarer in the US

quicklist: title: Retail E-Commercetext: The first and main category is Alibaba's retail marketplaces, which comprised 81.6 percent of the firm's revenue in its fiscal 2014 year, which ended in March.

This includes:

• Taobao, described as China's largest consumer-to-consumer shopping site, similar to eBay.

• Tmall, China's largest third-party business-to-consumer platform.

• Juhuasuan, China's most popular group buying marketplace.

Through these sites, Alibaba takes a cut when there's a transaction, plus there's the business of advertising and search results when people are looking for an item. Some vendors can pay more to be listed first in search results.

quicklist:title: Alibaba's Wholesale Marketplacetext: Alibaba's second biggest way to make money is its wholesale selling and buying business, which allows manufacturers to supply retail merchants. The website 1688.com is Alibaba's local wholesale business while Alibaba.com is involved in international commerce.

Alibaba's local wholesale business last comprised about 4.4 percent of revenue in 2014, while international commerce provided 9.2 percent.

quicklist:title: Paymentstext: As the folks at Apple can attest to, with its introduction of Apple Pay last week, the online and mobile payments industry is only getting started. Alibaba previously spun off Alipay, which describes itself as the "China's leading third-party online payment solution," and is similar to PayPal. But it's still in the Alibaba ecosystem, facilitating business in both the retail and wholesale marketplaces.

"These guys facilitate the transactions," Rao said of Alipay, which is a big and an essential business in China, because "there is a big slice of unbanked and underbanked population there," especially in the non-urban areas.

quicklist:title: Alibaba's Ancillary Services text: Alibaba has its hand in a number of other services, such as cloud computing and online marketing, which comprise 3.3 percent of the company's revenue.

"Alibaba is getting into a number of other businesses, such as gaming, taxi service, ticketing, movie studios, among others," Rao said. "They first take a small minority position in these emerging growth areas before acquiring them fully or take a major position."

But other times, the company just takes a bite of the apple. Alibaba has invested in other companies with no sign of total domination yet, including the American ride-sharing firm Lyft and member shopping site ShopRunner.com.