@m0r016 Desktop Environment. Debian mpbl'y uses Gnome, which I personally wouldn't prefer to have. Installing other DE can make whole experience much better.

@bhaskarrijal Thank you for telling me. Isn't Debian's default desktop lighter on Linux? I feel light because I'm an Ubuntu user.

@m0r016 both Ubuntu and Debian use Gnome as their default DE. Gnome is considered pretty resource hog compared to other. In simple, it is pretty heavy but won't make any difference if your machine houses some good specs.