It is only six years and seven months since the dot.com bubble of the late 1990s went pop. The previous years had seen a bewildering array of strangely named start-ups command vast sums of cash from apparently hard-headed businessmen and women based on little more than vague promises of profits in the distant future.
This week, it looked like someone had pressed the rewind button when the internet behemoth Google snapped up YouTube for $1.65bn (£900m). The free-to-use video service showcases short clips of everything, from teenagers lip-synching pop tunes in their bedrooms to grown men fist-fighting, and is the fastest-growing site on the web. Its acquisition elevates Chad Hurley and Steve Chen, YouTube's founders, to the ranks of the super-rich.
But according to conventional industry wisdom, theirs is a fortune based on sound economic principles. This time, analysts say, unlike the start-ups of the Nineties, the new companies are already thriving enterprises. And they are being bought up by existing media companies - witness News Corporation's purchase of online community MySpace.
Perhaps the most important difference between then and now is the establishment of a functioning business model - companies have learnt how to turn the internet into cold, hard cash. Google sells $10bn worth of advertising a year, turning a profit of $2.4bn. Not bad for a company that 10 years ago was little more than a student research project. The other step change is that many companies are using the acquisitions to improve their existing businesses.
On Monday, Universal Music Group signed a distribution deal with YouTube, following CBS, which will offer news and sport. Google said it had signed deals with Sony BMG and Warner Music to offer music videos.
Larry Page and Sergey Brin Google
Estimated personal worth Combined fortune of £14bn
Age 33 (both)
In 1996, they were two Californian PhD students puzzling over a more convenient and efficient way to search for websites on the then embryonic worldwide web. Their idea of ranking sites according to popularity and importance was to prove perhaps the most incredible business innovation of the age. It has even been hailed a modern wonder of the world.
Today, Google has become not just a company but a verb - and a gateway into virtually any subject, service or product that exists. It is estimated that more than half of all internet inquiries go through the Google website. Under Page and Brin, the company has built a unique corporate culture with the philosophy Do No Evil. Employees are encouraged to spend 20 per cent of their time on projects that interest them. At just 33 years of age, the two are now among the richest people on the planet.
Mark Zuckerberg Facebook.com
Estimated personal worth (based on market capitalisation) At least £530m
Mark Zuckerberg launched Facebook in 2004 as a user-friendly social directory to overcome the notoriouslystand-offish culture at Harvard, where he was a student. The idea caught on like wild fire. By now Facebook - a sort of MySpace for higher education - has almost 8 million registered users on more than 2,000 campuses. Zuckerberg, an enthusiastic programmer who happily skips meals and sleep for his passion, has taken a leave of absence from Harvard and bases his company out of California's Silicon Valley. He is the product of a wealthy background and elite schooling at establishments such as the Phillips Exeter Academy in New Hampshire, about the closest thing to Eton. Last month, he was reported to have turned down a $1bn buyout offer from Yahoo!, with rumours suggesting he asked Yahoo! to double its offer.
Robin Li Baidu.com
Estimated personal worth (based on market capitalisation) Around £1.6bn
Baidu.com is a Chinese search engine that remains the undisputed market leader in its home country, despite attempted inroads made by the likes of Yahoo! and Google. Because of the size of the Chinese market, it is the fourth most-visited website in the world. Robin Li was a graduate of Beijing University who came to the United States to pursue postgraduate studies after the Chinese government crackdown in Tiananmen Square. By the late 1990s, he was a disgruntled employee at Disney's portal Infoseek.com, and looking for a venture of his own. As the dot-com bubble burst, he took $1.2m (£640,000) in start-up capital back to China and took advantage of the burgeoning local economy to become his very own powerhouse. Baidu works much like Google, but has its own features such as a popular multimedia search function.
Chad Hurley and Steve Chen Youtube.com
Estimated personal worth (based on market capitalisation) £265m-£530m each
Age 29 (Hurley) and 27
Chad Hurley and Steve Chen may command a staff of just 67 but that didn't stop Google swooping on their business start-up this week for $1.6bn. Both were employees of PayPal, the online secure payment service, who came together in February 2005 with another PayPal colleague, Jawed Karim, to found what was destined to become one of the fastest-growing websites ever. YouTube, based near San Francisco, is a free video service giving users access to anything from funny moments from the week's television to home videos shot with mobile phones. Hurley is the designer; Chen and Karim were students in the University of Illinois' computer science department. They started their business in a garage, but were given a jolt when Sequoia Capital - the Silicon Valley venture capital firm that helped bankroll Yahoo! in the 1990s - injected first $3.5m and then $8m. The company uploads 65,000 new videos a day and around 100 million clips are viewed each day. Karim has left to pursue an advanced degree at Stanford.
Michael Birch Bebo
Estimated personal worth (based on market capitalisation) In excess of £160m
An ex-pat Brit living in San Francisco, Birch came up with Britain's answer to MySpace and Facebook. Bebo is a social networking site that is particularly popular among schoolchildren and university students. The service was launched in July 2005 and is already estimated to have 25 million users. In Britain, it is second only in popularity to MySpace. In Ireland, where it took off with particular verve, it clocks as many as 20 million page clicks per day. Birch, along with his wife and partner Xochi, was wise to the social-networking buzz very early on. His first venture, called Ringo.com, was an early foray into the field which he later sold to Tickle, now part of the recruitment site Monster. Viacom is reported to have offered him $750m for the new company, which he turned down. Other valuations put Bebo at a minimum of £160m.
Nick Denton Gawker Media
Estimated personal worth (based on market capitalisation) About £145m
An Oxford-educated Brit, Denton started writing about blogs as a reporter for the Financial Times, where he was a foreign correspondent and wrote a book about the collapse of Barings Bank. A huge internet fan, he made the transition from blog analyst to blogger and then blog entrepreneur. Gawker Media is an umbrella for several blog enterprises, including Gawker (Manhattan news and gossip), Wonkette (Washington politics), Defamer (showbiz gossip) and Fleshbot (pornography). Denton has played the society card adeptly, appearing in a Vanity Fair photoshoot and schmoozing with Arianna Huffington, another former journalist turned blog entrepreneur. His celebrity-sighting Gawker Stalker site provoked a response from George Clooney who urged his fans to flood the site with bogus sightings to discredit it.
Niklas Zennström and Janus Friis Skype and Kazaa
Estimated personal worth (partly based on market capitalisation) In excess of £688m each
Age 40 (Zennström) and 30
Zennström, a Swedish business and computer-science graduate, and Friis, a self-made Danish entrepreneur with no formal higher education, first hooked up at Tele2, a pan-European telecom operator, then went on to co-found two of the highest-profile peer-to-peer web services of recent years: Kazaa and Skype. Kazaa emerged in the wake of the Napster file-sharing controversy and offered web-users a similar function: sharing MP3 files, videos and other applications over the web and downloading them from one computer to another. They sold it to an Australian company before the inevitable lawsuits started flying and are now footing many of the legal bills. Altogether more successful was Skype, the free Internet telephone service, which they recently sold to eBay for $2.6bn.
Tom Anderson and Chris DeWolfe MySpace
Estimated personal value
About £148m each
Age 30 (Anderson) and 40
Nothing like a literary critic to start a web craze. Tom Anderson, left, a graduate both of the rhetoric and English programme at the University of California's Berkeley campus and the film school programme at UCLA, hooked up in 2003 with a business-school whizz called Chris DeWolfe and together they formed MySpace - now virtually a synonym for social networking online. MySpace is where people of all ages tell the world about themselves, post photographs, lists of favourite records and films, and invite friends to come visit and leave messages. By now it is the fourth-most popular English-language website and the sixth-most popular worldwide. Based in Santa Monica, California, its parent company, Intermix Media, was bought by Rupert Murdoch's News Corporation in July last year for $560m. It seemed a lot of money at the time but now looks like the bargain of the new century.
Andrew Black Betfair
Estimated personal wealth £100m, company valued at peak at £1.5bn
Launched on Oaks Day in 2000, Andrew Black and his partner, Jeremy Wray, warned their new Internet betting exchange would spell the end for the traditional bookmakers. Betfair allows punters to bet against each other at more favourable odds than High Street bookies, with the company taking a percentage of the winnings. Business was brisk from the off, with £35,000 of bets placed in the first week. But demand has soared. In 2005 the industry was worth £5.2bn in the UK. Betfair has seen its profits grow by 146 per cent a year from £1.6m in 2002 to £23.2m in 2005. More than 400 people are employed in the business and a recent offer by a Japanese technology group valued Betfair at £ 1.5bn. However,profits look set to fall after the US Senate announced legislation that will outlaw payments to online betting sites.