- Qt is a cross-platform application framework that includes an intuitive C++ class library and integrated development tools to build applications for desktop and embedded platforms. - The Qt class library provides core classes for GUI, SQL databases, XML, networking and more. It includes signals and slots for inter-object communication. - Qt Development tools include Qt Designer for GUI layout, Qt Linguist for internationalization, Qt Assistant for documentation, and qmake as a cross-platform build tool. Carbide.c++ provides support for Qt development on S60.