In the September 2015 survey we received responses from 892,743,625 sites and 5,438,101 web-facing computers. Both of these key metrics grew this month, with net gains of 18 million sites and 47,000 computers.

Microsoft made by far the largest gain in hostnames this month, with an additional 33.6 million sites bringing its total up to 265 million. Combined with a 15.9 million loss in Apache-powered sites, the difference between Microsoft's and Apache's market shares has now halved: Microsoft's share went up by 3.22 percentage points to 29.68%, while Apache's fell by 2.55 to 34.96%, reducing Apache's lead to just over five percentage points.

However, September's growth in web-facing computers paints a different picture, with Apache's net gain of 19,800 computers being more than six times higher than Microsoft's. Despite this, both Microsoft and Apache lost market share this month, while nginx – which gained the most web-facing computers in September (+22,100) – grew its share to nearly 13%. With an additional 6.9 million sites bumping its site share up to 15.60%, nginx was the only major server vendor to increase its market share in both sites and computers this month.

Despite no longer being supported by Microsoft, the number of websites using Microsoft IIS 6.0 (which typically runs on Windows Server 2003) has since grown by 19% and accounted for much of the overall Microsoft hostname growth this month. 153 million websites are now using Microsoft IIS 6.0, compared with 129 million in July; however, the number of web-facing computers using IIS 6.0 has fallen by 6%, and the number of active sites fell by 16%.

China accounted for around a third of this month's overall growth in web facing computers, outpacing the growth seen in the United States and Germany by a factor of three. Even so, China was responsible for only a tiny fraction of this month's site growth. Microsoft Windows continues to be the preferred hosting platform for computers in China, where it is currently used by 42% of all web-facing computers and 43% of all sites. Astoundingly, over half of these Windows computers are running Windows Server 2003, and some Chinese hosting providers continue to provide new installations of this deprecated operating system.

Amongst the world's top million websites, nginx has continued to increase its market share and now powers more than twice as many sites as Microsoft. Apache's share has been steadily declining over the past few years mostly as a result of nginx's gains, but it looks set to remain the dominant server vendor within the top million for a while longer, as it is still used by more than twice as many sites as nginx.

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