I believe your question contradicts! " Which programming launguage do you use for windows application? " contradicts with your subject for the thread "MOST USED PROGRAMMING LANGUAGE". Undoubtedly, the answer to the later one is C. C is the most used programming language for OSes, systems and all. For a windows application, i presume .. any platform that uses the windows API would be considered to be a candidate for the most widely used language. .NET platform now, VB then .. perhaps win the title.