The Nintendo Entertainment System (commonly abbreviated as NES) was the first Nintendo home console released in America. It plays 8-bit cartridge type games on a TV. It is considered to have been advanced for its time, compared to the Atari 2600. One of the first games released was Super Mario Bros.. This is the system that made Mario popular, and the first major step towards Nintendo's rise in the gaming market. The NES is also the origin of a number of Nintendo's other main franchises, including the Legend of Zelda and Metroid series. Its sequel is the Super Nintendo Entertainment System.
In Japan, the Famicom (Family Computer) was released before the NES. Its functionality is essentially the same since it's basically the same system in a different shell, but it has extra features, including microphones built into the controllers.
The Famicom Disk System is an add-on for the Famicom released exclusively in Japan, where games are sold and stored on rewritable floppy discs. Super Mario Bros.: The Lost Levels was released as Super Mario Bros. 2 in this format.