C IS A programming language devleoped at at and t bell labs.it was initially developed by DENNIS RITCHIE(rip).there are a lot of software written in c, to view those just try the link ( http://en.wikipedia.org/wiki/Category:Free_software_programmed_in_C). A very famous software we all use in our daily life is vlc media player programmed in c.the reason for becoming c to be so popular because it is very easy to use.major parts of popular operating systems such as windows, unix , linux are written in c. although there are many languages today such as java , c++ , c# ( pronounced c sharp), but today also c is very popular in programmers because of its speed of execution. and also we can use c for developing apps for some os like for windows phone 8 we have visual studio framework.