Editor's Note: Inc. Magazine announced its pick for Company of the Year on Monday, November 23. It's Slack! See which one Inc. readers chose as their favorite company of 2015. Here, we spotlight Uber, one of the contenders for the title in 2015.

Just six years old, Uber is the world's most highly valued private company. And it's quite possibly the fastest-growing ever. It reached a $50 billion valuation three years faster than the only startup to have ever done so in the past: Facebook. It has become not just a company extremely admirable in its growth, but, well, the very model for how to do things when you're scaling a company.

But really, let's be honest, this is a very young company. Its founder and CEO, Travis Kalanick, intoned as much at a Wall Street Journal conference last month in Laguna Beach, California, saying we all need to stop thinking of it as some fully mature corporation. He wants to quash rumors that the San Francisco-based company is gearing up for the ultimate grownup move: a public offering. "We're maturing as a company, but we're like eighth graders," he said. "It's just a little early--give us a few years."

Seems Uber is the most hulking gradeschooler on the planet.

It has 1.1 million drivers in 330 cities around the globe. It also recently hired the person responsible for managing the campaign that put the president of the United States in the Oval Office and the person responsible for keeping Facebook secure. In other words, just when we thought that Uber had been embracing its new role as one of the big guys, it now says, nope, not so fast. Uber itself thinks it has a long way to go. And, indeed, it does. This next year for Uber holds as much promise for the company as its first five put together.

While the company is nearly ubiquitous in cities here in the United States and all over Europe, it's just warming up in China, India, and beyond. It was just a year and a half ago when Uber picked a Chinese name (??, or You Bu) and officially launched in China. 

Analysts say that Uber has about one-third the ridership of its primary competitor in China, Didi Kuaidi. And yet, it's already doing a full one-third of its global business there. (Yes, you read that right: In less than two years, the company is already completing as many rides in China as it does in the whole United States.) Moreover, Kalanick recently told The Wall Street Journal that one of the biggest Uber-riding cities in China is Chengdu. Fourteen months after the Chengdu launch, that market was already 100 times bigger for Uber than San Francisco was after a year of doing business there. 

So if Uber is a gradeschooler in the U.S., it's still just a toddler in Asia--albeit, a toddler on an intensive regime of HGH. And there is a lot of growth to go.

Same goes for India, where Uber set up shop in mid-2013. It already has more cities there than any other country, aside from the United States. Yet the entire region is in its sights. Uber earmarked more than $1 billion to face regulatory fights in Thailand, Singapore, and Vietnam, over the last year. It's even hiring in Pakistan.

It's also still raising money at a furious pace. The company is reportedly planning another billion-dollar raise--marking the eighth round of funding it has sought in the past five years.

Uber's China ambitions only seem more impressive when one considers that historically, it has been difficult for American tech companies to do business there. Small companies can be hampered by it or crushed. Even the biggest ones sometimes avoid it altogether. Google and Facebook--for the most part--don't touch it. 

Uber's not just touching it. Uber is going to make huge progress in China over the next year. For that, it may be not just the biggest--or the fastest-growing--but also the most fascinating private company on the planet to watch this year.