Microsoft's Internet Explorer and Google's Chrome both gained market share during April, with Mozilla Firefox and Apple's Safari losing out. The Firefox numbers are bad news for another reason, too: Firefox users are leaving themselves open to exploitation with about a third appearing to use obsolete, unpatched versions of the browser with known security flaws.

Internet Explorer picked up 0.26 points for a 54.09 percent share of the desktop market. Chrome gained 0.28 points giving it a 18.85 percent share. Firefox dropped 0.35 points for a 20.2 percent share, and Safari lost 0.26 points, dropping to 4.81 percent. Opera was essentially unchanged, up 0.01 points to 1.63 percent.

Chrome suffered setbacks earlier in the year, both due to losing its positioning in Google's search results and changes to Net Market Share's data collection policy to exclude pre-rendered pages. The browser's position in searches has now been reinstated, and the hit from excluding pre-rendered pages was a one-off correction, leaving it free to resume climbing.

Mozilla, meanwhile, continues to see Firefox's market share drop. At current rates, Firefox will represent less than one in five Internet users next month. It seems that new computer users simply aren't using the Mozilla browser as much as users of old machines. By the end of last month, Windows 7 users showed high uptake of both Internet Explorer 9 (35.5 percent of users) and Chrome 18 (21.0 percent of users). Firefox 11/12, however, managed to pick up only 15.3 percent of users. A few Windows 7 users might be sticking with old versions of Firefox, but this is unlikely to be common: only the Extended Support Release of Firefox 10 and latest Firefox 12 are actively maintained and supported. Windows 7 buyers are still interested in non-Microsoft browsers; they just seem to want Google's browser more than Mozilla's.

March was a bumper month for Internet Explorer 9 usage, as it leapt by 2.6 points. April was rather quieter: that version's share grew, but it only picked up 0.71 points. Internet Explorer 8 also gained, picking up 0.49 points. Pleasingly for Web developers, both Internet Explorer 6 and 7 lost share, falling by 0.44 and 0.48 points respectively. Microsoft is continuing to advertise the newest version of its browser, and continuing, belatedly, to push automatic updates for the browser.

April was an important month for Firefox's updates, though you wouldn't know it from looking at its adoption graph. Firefox 12 was released on April 25th. This had two effects. First, Firefox 12 includes a streamlined update system for Windows users. Upgrading Firefox no longer triggers a UAC prompt; you simply restart the browser and the new version automatically installs. The process still isn't seamless the way Chrome's updates are, but it's a lot less invasive and a lot more convenient than it once was.

Also triggered by the release of Firefox 12 is the end of support for Firefox 3.6.x. Firefox users wanting to receive security updates must now install either the Firefox 10 Extended Service Release, or Firefox 12. Unfortunately, Firefox has a long tail of non-upgraders. 5 percent of Firefox users are still using a 3.5 (or older) build; 3.5 was last updated on April 28th, 2011. Another 16 percent of Firefox users are still on versions 4 through 9, which similarly aren't receiving security updates. Even assuming that all Firefox 10 users are on the latest ESR build, fully 33 percent of Firefox users are using a version of the browser with known security flaws.

Chrome's consistent, high-uptake updates continue to be unmatched by its rivals. If nothing else, this shows the importance of having automatic updates from day one: it makes it much harder for people to get stuck on old, manually-updated versions of the software. There does remain a hardcore set of 12 percent of Chrome users that insist on using ancient versions of the browser, however.





The mobile browsing market continues to show considerable volatility. Android's browser is starting to pull away from Opera Mini, but Safari remains dominant. Net Market Share reports that the iPad has overtaken the iPhone; although there are far more iPhones in people's hands than there are iPads, the browsing experience of the tablet is, unsurprisingly, preferred to that of the phone.





Google's dominance at Ars continues unabated, with both Chrome and Android stretching their leads.