This is a GNOME theme featuring the Clearlooks engine.
The installation process is a breeze. All you need to do is right-click on your desktop and choose Change Desktop Background. Then, navigate to the Theme tab and drag and drop the theme archive in the Appearance Preferences window. Once the installation is complete, you will receive a confirmation message, and you can activate the theme by selecting it.
GNOME is an international project that aims to develop a complete desktop environment entirely from free software. This includes creating software development frameworks, selecting application software, and working on programs that manage application launching, file handling, as well as window and task management.
GNOME is a part of the GNU Project and is compatible with various Unix-like operating systems, mainly Linux, and can be used with Java Desktop System in Solaris. While the name originally stood for GNU Network Object Model Environment, it is now deprecated. The GNOME team focuses on simplicity, usability, and making things easy to use for everyone.