The most used language on the Internet is unknown, although about half of the homepages of the most visited sites on the Internet are in English, with varying amounts of information available in many other languages.
There is debate over the most-used languages on the Internet. A 2009 UNESCO report monitored the languages of websites for 12 years from 1996 to 2008 found a steady year-on-year decline in the percentage of webpages in English from 75% in 1998 to 45% in 2005. The authors found that English remained at 45% of content for 2005 to the end of the study, but believe this was due to the bias of search engines indexing more English-language content rather than a true stabilization of the percentage of content in English online.
Ongoing monitoring by W3Techs showed that in March 2015, just over 55% of the most visited websites had English-language homepages. Other top languages that are used at least in 2% of the one million most visited websites according to W3Techs are Russian, German, Japanese, Spanish, French, Chinese, and Portuguese.
Note, however, that the figures from the W3Techs study are based on the one million most visited websites (i.e., approximately 0.27% of all websites according to December 2011 figures) as ranked by Alexa.com, and language is identified using only the home page of the sites in most cases (i.e., all of Wikipedia is based on the language detection of http://www.wikipedia.org). As a consequence, the figures show a significantly higher percentage for many languages (especially for English) as compared to the figures for all websites. The figures for all websites are unknown, but some sources estimate below 50% for English: see for instance, Towards a multilingual cyberspace and the 2009 UNESCO report referenced earlier.
The number of non-English pages is rapidly expanding. The use of English online increased by around 281% from 2001 to 2011, a lower rate of growth than that of Spanish (743%), Chinese (1,277%), Russian (1,826%) or Arabic (2,501%) over the same period.