Qt is a powerful, cross-platform framework widely used for developing applications with graphical user interfaces (GUIs), though it also supports non-GUI programming. Originally developed by Trolltech in 1991 and now maintained by The Qt Company, it is primarily written in C++ and allows developers to create software that runs on multiple platforms, including Windows, macOS, Linux, Android, and iOS, with minimal code changes. Qt provides a rich set of libraries and tools, such as Qt Creator (an integrated development environment), making it easier to design intuitive and responsive user interfaces. Its key features include a robust signal-slot mechanism for event handling, extensive widget collections, and support for 2D/3D graphics, networking, and database integration. Qt is popular in industries like automotive, medical, and gaming due to its flexibility, performance, and ability to streamline the development of complex, high-quality applications.