Millions download latest Firefox browser
More than five million people have downloaded the latest version of Firefox since its release a day ago.
Mozilla, which makes the number two web browser, has been keeping a real-time map showing where in the world users are installing the software.
Despite the rapid uptake, downloads have been slower for version 4 than its predecessor.
Over the past year, Firefox's market share has declined slightly in the face of competition from Google's Chrome.
Firefox 4 was made available for download less than a month after Microsoft launched Internet Explorer 9, the latest version of its market-leading browser.
Both pieces of software promise users a faster, more secure online experience.
Firefox, like its rival, now makes extensive use of HTML 5 - the newest standard for the hypertext language used to build websites.
Both browsers also feature hardware acceleration for displaying web pages - drawing on the power of a computer's graphics processor to improve the speed of complex visuals.Declining share
Within its first 24 hours, more than 5.5 million users had downloaded Firefox 4. However, that falls short of the 8 million who downloaded version 3 on its release day in 2008.
The lower figure may be explained by the widespread availability of pre-release versions of Firefox 4 in the months ahead of its launch.
Firefox has enjoyed rapid growth since it first appeared in 2004. At its peak, in 2009 it held a 24% market share, according to Netmarketshare.
However, by February 2011 its slice of the browser market had fallen to 21%.
At the same time, Google's Chrome browser has grown from 1% to 10%, according to the same figures.
Internet Explorer remains the dominant platform, although its fall has been the most precipitous - from 68% in March 2009 to 56% in February 2011.
Some analysts believe that Firefox could still secure a bigger piece of the increasingly fragmented market, especially among corporate users.
"Internet Explorer 9 is only for Windows Vista and 7. Two thirds of companies are still using Windows XP," said Ovum analyst Richard Edwards.
"If you want to make the most of the HTML 5 stuff that is out there then you have to go to IE9 and a Windows 7 upgrade or switch to Firefox.
"That may be a significant opportunity for Firefox," he said.