GTK
GTK (formerly GTK+) is a free and open-source cross-platform widget toolkit for creating graphical user interfaces (GUIs). It provides a comprehensive set of widgets, such as buttons, windows, and menus, and is primarily used for developing desktop applications on Linux, macOS, and Windows. The toolkit is written in C but supports bindings for many programming languages, including Python, JavaScript, and Rust.
Developers should learn GTK when building native desktop applications, especially for Linux environments where it is the standard for many distributions like GNOME. It is ideal for creating lightweight, performant GUIs with a consistent look and feel across platforms, and is commonly used in open-source projects such as GIMP, Inkscape, and GNOME applications. Use cases include developing system tools, media players, or any application requiring a robust, customizable interface.