Qt is a popular framework used for developing cross-platform applications. It provides tools and libraries that allow developers to create software that can run on various operating systems, such as Windows, macOS, and Linux, without needing to rewrite the code for each platform. The framework supports both graphical user interfaces (GUIs) and non-GUI applications, making it versatile for different types of projects. Qt is written in C++ and also offers bindings for other programming languages, such as Python, enabling a wider range of developers to use its features effectively.