Windows 8 passed a milestone of sorts in June, passing Windows Vista's market share to become the third most-used version of Windows on the Internet. Internet Explorer 10 continued to show strong growth too, fueled this time by automatic updating.

Google Chrome put in a strong performance, offsetting losses made earlier in the year. Its growth was to the detriment of Mozilla's Firefox, which fell significantly.

Microsoft's browser made a slight gain, up 0.16 points to 56.15 percent (a two year high). Firefox was down 1.48 points to 19.15 percent—the lowest share the open source browser has seen for more than two years. Chrome rose 1.43 points to a 17.17 percent share. Safari was more or less unchanged, up 0.09 points to 5.55 percent. Opera lost 0.19 points for a share of 1.58 percent, a level not seen since August last year.

Part of this swing is likely due to a change in how our data source, Net Market Share, counts traffic. Net Market Share has long had a policy of excluding pages that Chrome speculatively loads and renders but does not show to users. In June, it also started excluding pages that load in background tabs but are never subsequently viewed. This category included 6.38 percent of Firefox traffic, 6.33 percent of Opera traffic, 5.60 percent of Chrome traffic, 0.70 percent of Internet Explorer traffic, and 0.15 percent of Safari traffic.

This suggests that users of Firefox, Chrome, and Opera tend to have more tabs open than users of Internet Explorer and Safari. Further, these users likely have a bunch of tabs that persist from session to session but are not consistently viewed. Internet Explorer and Safari users, by contrast, appear to have fewer tabs but actually read almost all the tabs that they open.

In the mobile world, we're seeing the usual fluctuations. Safari was down 1.94 points to 58.04 percent; Android browser was down 0.15 points to 20.58 percent. Opera Mini, however, picked up 0.63 points for an 11.16 percent share.

Three browsers are showing some more consistent trends. Internet Explorer gained for the third month running, up 0.4 points to 2.37 percent. Chrome was up for the fifth month running, up 0.53 points to 3.75 percent. Opera Mobile fell for the fifth month in a row, down 0.09 points to 0.31 percent.

The implication here is that both "modern" Android (those versions that can run or, in particular, ship with Chrome as the default) and Windows Phone are starting to become a more significant presence on the Web.

The upgrade story is the same as always, with adoption of Internet Explorer 10 continuing to outpace the adoption of previous Internet Explorer versions. In June, IE posted its biggest gains yet, up 4.28 points for a total of 13.57 percent of the desktop Web. As with previous months, this came at the expense of Internet Explorer 9, which dropped 3.67 points to 11.72 percent during the same period.

This makes Internet Explorer 10 the second most-used version of Internet Explorer, behind Internet Explorer 8 at 22.75 percent. It's also the fourth most-used browser version overall, behind Internet Explorer 8, Chrome 27 (at 13.78 percent), and Firefox 21 (at 12.47 percent).

Windows 8 also had a good month. The operating system overtook Windows Vista, up 0.83 points for a 5.10 percent market share. This, in fact, marks the biggest one-month gain since the operating system went on sale. It also puts Microsoft's platform ahead of the two most recent versions of OS X.