In case you didn’t know, Nintendo has been around for a long time – over 100 years. They used to make playing cards for various games of Eastern and Western original. Eventually they became a pretty big toy company. In the 1960s, they became involved in the pre-video game arcade market with lightgun-type games. Then, they started doin’ video games.
Nintendo Research & Development 1
This was the original development team at Nintendo, under the leadership of the famed Gunpei Yokoi. They were involved in both game development and hardware design. Their most famous series/creations:
Donkey Kong
Metroid
Kid Icarus
Wario Land
Wario Ware
*and*
the Game Boy!
Nintendo Research & Development 2
This group’s emphasis was on hardware. As such, they didn’t really begin developing games until the mid-90s. Their best-known “creations” are the Super Mario updates for Game Boy Advance.
Nintendo Internal Research Division
Another team primarily concerned with hardware design but they did have 2 notable series: Punch-Out and StarTropics.
Nintendo Enertainment Analysis Disivion
The big heavy-hitting team responsible for the following creations/series:
Super Mario
Legend of Zelda
Mario Kart
StarFox
Animal Crossing
Pikmin
In 2004, Nintendo EAD swallowed up the other divisions so now there is ONLY Nintendo EAD, which is divided into many different teams under various leaders.
Another first-party developer of note:
Intelligent Systems
Developers of the long-running (but only recently introduced in America) series Nintendo Wars and Fire Emblem.