The tech world has a new darling du jour: It's Dropbox, a popular digital storage and file-sharing service. The company's founder and CEO, Drew Houston, earned the attention of the late Steve Jobs — and reportedly a 9-digit buyout offer — when he smartly reverse engineered the Mac operating system so the Dropbox logo "elegantly" and automatically appeared as a seemingly organic icon in the Apple menu bar. "Not even an Apple SWAT team had been able to do that," writes Victoria Barret in a Forbes cover story on the hot startup. Here, a brief guide, by the numbers, to Dropbox's rapid ascent:

50 million
Number of users Dropbox has in 175 countries. The San Francisco-based company is just 5 years old

4 million
Number of users Dropbox had in January 2010. A month earlier, Steve Jobs had summoned Houston and his partner, Arash Ferdowsi, to his Cupertino office. Jobs "presciently" saw that Dropbox could be a valuable asset to Apple, but Houston said he was determined to remain independent and expand. Jobs told Houston Dropbox was "a feature, not a product."

$800 million
Amount Apple's Jobs reportedly offered to pay for DropBox

$250 million
Amount of funding Dropbox secured from "seven of the Valley's elite venture firms" in August. "This is the hot company," says a well-known investor who didn't get a stake in the company

$4 billion
Value of the company, based on that venture-capital investment

$81 million
Amount of funding Dropbox competitor secured last week

325 million
Number of files that are saved to Dropbox each day

Number of users who join every second

$240 million
Revenue Dropbox is set to bring in for 2011. Houston says the company is already making a profit, but he won't divulge specifics

Percent of Dropbox users who pay nothing. Users get 2 GB of storage for free. For $10 a month they can upgrade to 50 GB; for $20, they get 100 GB

Current number of Dropbox staffers, most of them engineers

Number of staffers the company plans to have soon — "still an absurdly low number given the company's size," says Barret

Number of staffers it had in 2008

Number of rooms in the Dropbox office "on gritty Market Street" in San Francisco

Size of the office, in square feet, the company is soon moving to. The new digs will have views of San Francisco Bay

1 out of 4
Number of Dropbox users who come via referral. Instead of advertising, the company offers existing users 250 megabytes of free storage if they refer a friend

222 million
Number of people who have iPhones, iPods, and iPads, who may now use Apple's newly launched iCloud rather than Dropbox. Though Houston "believes Dropbox will torpedo the backup industry within five years, he especially fears iCloud," says Barret. At this point though, Dropbox "remains a hell of a great alternative" to using iCloud, says Sam Biddle at Gizmodo

Age of Dropbox founder and CEO Drew Houston

Age at which Houston first began playing with an IBM PC Junior

Sources: Cult of Mac, Forbes, Gizmodo, ZD Net Asia