The Arabic television news channel al-Jazeera has launched its new English-language station.
Al-Jazeera English began broadcasting from the station's headquarters in Doha, Qatar, at 1500 (1200 GMT).
A screen graphic with a clock ticking down the minutes gave way to a photo montage of the biggest news stories of recent years, including 9/11.
Al-Jazeera in Arabic is known for its forthright style, frank journalism and willingness to discuss taboo issues.
This has made it a thorn in the side of governments from Washington to Riyadh, says the BBC's Ian Pannell in Cairo.
After the opening credits, presenters Shiulie Ghosh and Sami Zeidan ushered in the new channel, saying it would be "setting the news agenda".
"It's November 15th, a new era in television news."
The channel then went to images of correspondents in various locations including Gaza then Sudan's Darfur region, followed by Iran and Zimbabwe.
As it went on air, the channel had to contend with a breaking news story on a tsunami expected to hit Russia and northern Japan.
'Middle Eastern feel'
Al-Jazeera English will initially broadcast for 12 hours a day before becoming a 24-hour news operation from 1 January.
It will broadcast from studios in Doha, Kuala Lumpur, London and Washington DC, in addition to 20 other countries.
It will be available to 80 million homes - double its target audience - in Europe, Africa and south-east Asia.
In the United States, the channel will be available via a broadband internet connection, but not distributed by a major cable or satellite system.
Originally due to launch in 2005, the station employs some 800 people from 55 countries and hopes to bring a different perspective to international events.
It is definitely an international channel, but it's certainly going to have a Middle Eastern feel about it," one of the channel's presenters, Felicity Barr, told the BBC.
"The instant reaction for, say, a Western organisation, is to get analysis from the United States or from the UK," she explained.
"We will be getting our reaction, first and foremost, from the Middle East."
The channel is hoping to revolutionise English-language television in the same way it revolutionised Arabic-language television 10 years ago.
But our correspondent says this will be a much harder task.
Al-Jazeera's achievement in the Middle East was to break a monopoly on information held by governments and state broadcasters, our correspondent says.
But the international market is already much more developed with well established rivals in the BBC and CNN.
"One of our goals is to reverse the flow of information to the south," Wadah Khanfar, director general of the al-Jazeera Group explained to Reuters news agency.
While the hope is that a major English-language channel operating from the Middle East will give the Arab world a global voice, our correspondent says the launch will simply be a moment of pride.
But, he adds, the question for some in the region is whether the new channel will be as outspoken as its sister station and whether it will adopt a similar editorial stance.