How widespread is the use of C programming? (After all, C has been around since the 1970s.) Well, it seems to be surprisingly popular still. Look at the first chart (Google Hits per Language) in a paper by David N Welton - note where C stands in a table reflecting the web visibility of a large number of computer programming languages.
FOLDOC (Free On Line Dictionary Of Computing) Large list of computer-related definitions. Occasionally this site is not fully available and then choose one of the links found in a Google search for "foldoc". The C+- entry is somewhat special for C++ programmers and other humans...