Ubuntu is a predominantly desktop-oriented Linux distribution, based on Debian GNU/Linux but focused on usability and frequent releases, at the expense of platform diversity and openness.

There are various variants including Kubuntu, Xubuntu, Lubuntu, Ubuntu Budgie, Ubuntu Studio, etc...

Ubuntu for Debian developers

Ubuntu inherits to some extent Debian packages. Some of them are just rebuilt; some others may be heavily modified with respect to Debian. For Debian Developers interested in learning more about the fate of their packages in Ubuntu, there is a page in the Ubuntu wiki meant to collect all information useful to Debian Developers: