Qt is a toolkit for software developers. Qt project simplifies the task of writing and maintaining GUI (graphical user interface) applications. It is written in C++ and is fully object-oriented.
It is a multi-platform toolkit. When you implement a program with Qt, you can run it on the X Window System (Unix/X11), Apple Mac OS X, and Microsoft Windows NT/9x/2000/XP by simply compiling the source code for the platform you want.
One of the key design goals behind Qt is to make cross-platform application programming intuitive, easy and fun.
Qt achieves this goal by abstracting low-level infrastructure functionality in the underlying window and operating systems, providing a coherent and logical interface that makes sense to programmers.
The Qt API and tools are consistent across all supported platforms (see below for details), enabling platform independent application development and deployment. | 
