|This article relies too much on references to primary sources. (October 2010)|
TIOBE programming community index is a measure of popularity of programming languages, calculated from number of search engine results for queries containing the name of the language. The index covers searches in Google, Google Blogs, MSN, Yahoo!, Baidu, Wikipedia and YouTube. The index is updated once a month. The current information is free but the long term statistics over many years of observation is for sale. The index authors think that it may be valuable when accepting various strategic decisions. TIOBE focuses on Turing complete languages, so it does not provide information about the popularity of, for instance, SQL or HTML.
According to the site, TIOBE index is "not about the best programming language or the language in which most lines of code have been written". However the site does claim that the number of web pages may reflect the number of skilled engineers, courses and jobs worldwide.
Pierre Carbonnelle challenges TIOBE's naming of Objective-C as the "programming language of the year" in 2012, arguing that there may be many Objective-C pages on the web, but they are rarely read. It proposes its own PYPL index instead, based on Google Trends data. It shows popularity trends since 2004, worldwide and for 5 different countries.
TIOBE index is sensitive to the ranking policy of the search engines on which it is based. For instance, in April 2004 Google performed a cleanup action to get rid of unfair attempts to promote the search rank. As a consequence, there was a huge drop for languages such as Java and C++, yet these languages have stayed at the top of the table. To avoid such fluctuations, TIOBE now uses more search engines.