● Stands for "Gimp Toolkit."

● A free and open source cross-platform widget toolkit for creating graphical user interfaces (LGPL License).

● Built on top of GDK (GIMP Drawing Kit) which is basically a wrapper around the low-level functions provided by the underlying windowing and graphics system.

● One of most popular toolkits for Wayland and X11 windowing systems. Also works on Windows and macOS (interfacing with Windows API / Quartz).

● Originally written, along with Gimp, by Peter Mattis and Spencer Kimball in 1995 for a project at UC Berkeley in CA. As they wrote Gimp, Peter didn’t like motif, so he wrote Gtk to replace that.

● Later, Gtk was re-written to support some object-oriented features and was then renamed to Gtk+. It later became adopted by the GNOME Foundation. Some began calling it "Gnome Toolkit". In Feb 2019, they dropped the "+". It’s just "Gtk" again.

● Desktop application

● Preferably cross-platform

● Many options:

• Qt
• WxWidgets
• Others I may still try (not yet convinced by Gtk)