LXDE, the "Lightweight X11 Desktop Environment", is an extremely fast, performant, and energy-saving desktop environment. It maintained by an international community of developers and comes with a beautiful interface, multi-language support, standard keyboard shortcuts and additional features like tabbed file browsing.
LXDE is not designed to be powerful and bloated, but to be usable and slim. A main goal of LXDE is to keep computer resource usage low. It is especially designed for computers with low hardware specifications like netbooks, mobile devices (e.g. MIDs) or older computers.