WordPress powers 27% of the internet.
Unfortunately no source is provided for that statement. Is this number true?
This number comes from W3Techs - World Wide Web Technology Surveys.
According to that survey, as of December 2016,
WordPress is used by 27.2% of all the websites
that they monitor. (Source.)
As they note:
When interpreting our surveys, you should know the following:
- We investigate technologies of websites, not of individual web pages. If we find a technology on any of the pages, it is considered to be used by the website.
- We include only the top 10 million websites (top 1 million before June 2013) in the statistics in order to limit the impact of domain spammers. We use website popularity rankings provided by Alexa (an Amazon.com company) using a 3 months average ranking. Alexa rankings are sometimes considered inaccurate for measuring website traffic, but we find that they serve our purpose of providing a representative sample of established sites very well.
- We do not consider subdomains to be separate websites. For instance, sub1.example.com and sub2.example.com are considered to belong to the same site as example.com. That means for example, that all the subdomains of blogger.com, wordpress.com and similar sites are counted only as one website.
(Also see their disclaimer for further caveats.)
While the number is real it means (as per other answer) something different in W3Techs report (source for it) — share in top 10 million sites by traffic sample.
But that doesn't say if the number is true or close to true for global market share.
I had looked into other possible estimates for my blog post on topic:
So while the number is real for specific sample of sites, applying it to whole web market share seems like a stretch and makes result inconsistent with other sources.
There is also huge variation possible depending on how hosted WordPress.com sites are counted. They make a very significant portion of total WordPress sites but are counted as a single site if subdomains are not considered.