Debian has surpassed CentOS to become the most popular Linux distribution on web servers.
Debian lost that #1 position in June 2010 to CentOS and gained it back now, after a head-to-head race in the last year.
Debian is now used by 9.6% of all websites (up from 8.9% one year ago, and 8% two years ago), which is equivalent to 29.4% of all Linux-based sites.
It is also the fastest growing operating system at the moment: every day 54 of the top 1 million sites switch to Debian.
This growth comes primarily from websites that are starting to use Linux, because we see in the technology change report that many sites subsequently switch from Debian to the Ubuntu distribution (which is based on Debian). Debian gains market share from all other Linux distributions, mostly from CentOS, SuSE and Fedora.
Debian is a little bit less popular amongst high traffic sites, but 8.5% of the top 1000 sites is still very strong.
If we look at which web servers run on Debian boxes, we see that Nginx and Lighttpd servers very often run on top of Debian (almost 60%), however Apache still is by far the most popular web server when we look at all Debian servers.
An overwhelming majority of all Linux servers use PHP as server-side language, and Debian is no exception: 97.5% of the websites served from Debian are written in PHP. Around 30% of those use one of the common PHP-based content management systems.
Looking at the geographical distribution of Debian sites, we see that Debian is extremely popular in Europe: Germany 39.7% of all sites, Poland 36.1%, France 33.6%, Russia 26.4%, and much less popular in Asia: Japan 1.9%, India 1.8%, China 0.5%. Debian usage is also below average in USA and Canada.
Preferences of Linux webmasters tend to change relatively quickly. We have seen the haed-to-head race between CentOS and Debian, but also the raise of Ubuntu as server system. At the moment Debian is on top, let's check again in a few months.