Mark Zuckerberg has showcased the "Facebook phone" as he revealed the social networking site could now become the central feature on Android mobiles.
At a highly-anticipated event at the company's Menlo Park headquarters in California, he said consumers would be offered something far more than an "ordinary app" - an entirely "new experience" called Home.
He said: "We are not building a phone and we are not building an operating system, but we are are building something that is a whole lot deeper than an ordinary app."
Wearing one of his customary hooded jumpers, Mr Zuckerberg gave a relaxed presentation telling his audience: "We're really proud of Home and we're excited to get it in your hands ... we think that this is the best version of Facebook there is."
He was joined by Peter Chou, the chief executive of handset maker HTC, to reveal the companies' collaboration to produce HTC First - the only phone which will come with Facebook Home already installed.
In a short explanation of how Home would work, Mr Zuckerberg said: "The homescreen is really the soul of your phone. You look at it about a hundred times a day. It sets the tone for your whole experience and we think it should be deeply personal. So today we're going to talk about this new experience for your phone. It's a family of apps and you can install it and it becomes the home of your phone.''
In a short demonstration, Mr Zuckerberg showed viewers how the new product would appear on the homescreen of an Android phone and offered users the "highest quality experience''.
He added: "At one level, this is just the next mobile version of Facebook but at a deeper level, I think that this can start to be a change in the relationship that we have with how we use these computing devices. For more than 30 years computers have mostly just been about tasks and they had to be... but the modern computing device has a very different place in our lives.
"It's not just for productivity and business although it's great for that too. It's also for making us more connected, more social, more aware. And Home, by putting people first, and then apps, by flipping the order is one of many small but meaningful changes in our relationship with technology.''
Home will be available for download or on the HTC model from April 12, he said. HT First will be available with EE in Britain in the summer. No details have yet been given as to its price.
Forbes rich list: the world's top ten billionaires
'Facebook phone' project unveiled
The Mexican self-made telecoms mogul tops the rich list with a wealth that, as Forbes reports, if it were a country would be the eighth richest in Latin America.
Dubbed the world's most generous person, Bill Gates made his fortune as the brains behind Microsoft and has reportedly already donated $28 billion of his wealth to charity so far.
Spanish billionaire Ortega is the man behind the clothes brand Zara and is this year's biggest rich list gainer, making $19.5 billion last year and moving him into third position.
Buffett made his billions as CEO, primary shareholder and chairman of Berkshire Hathaway, A diversified company with interest in GEICO, life insurance, annuity sales and sales of jewellery. He recently signed a lucrative deal to acquire Heinz Ketchup.
Ellison founded Oracle Corporation, a leading enterprise software company. He's America's third richest man and Forbes has reported that he recently bought 98% of the Hawaiian island of Lanai from David Murdock for a reported sum of $500 million.
Koch built his fortune on chemicals and refining and shares the sixth position on the rich list with his billionaire brother, David Koch.
Tied sixth in the rich list with his elder brother Charles, David runs the chemical equipment side of Koch Industries from his New York home.
This self-made billionaire is Asia's richest man and currently supplies a quarter of British people with gas after acquiring British gas supplier Wales & West Utilities for $1 billion last October.
The only woman in the top ten, Bettencourt's father founded L'Oreal and now she and her family own 30% of the French cosmetics super brand.
Branded by Forbes as the 'World's most influential tastemaker' Arnault owns the luxury goods powerhouse LVHM, Moet Hennessy - Luis Vuitton.