"The Nintendo DS is a dual-screen handheld game console developed and manufactured by Nintendo. It was released in 2004 in Canada, the United States, and Japan. The console features a clamshell design, similar to the Game Boy Advance SP, with two LCD screens inside—with the bottom one being a touchscreen. The Nintendo DS also features a built-in microphone and supports wireless IEEE 802.11 (Wi-Fi) standards, allowing players to interact with each other within short range (10–30 m, depending on conditions) or online with the Nintendo Wi-Fi Connection service, which launched later in the console's lifespan. This was the first Nintendo console to be released in North America before Japan.

The Nintendo DSi is an enhanced version of the DS, adding two digital cameras, a digital distribution mechanism, and an SD card slot, but loses the GBA cartridge port. "

Source: Wikipedia, "Nintendo_ds", available under the CC-BY-SA License.

Region Locking:
Nintendo DS consoles are not region locked and games can be played on any system that reads standard Nintendo DS cartridges.
DSi consoles and software are region locked. While a DSi system will play an DS software, it will only play DSi software sold in the same region. This restriction also applies to software sold vie the DSi-Ware store.

Compatibility
Nintendo DS consoles can play standard Game Boy Advanced cartridges. It will not play Game Boy or Game Boy color cartridges.
DSi consoles lack the GBA cartridge slot, and can not play GBA games.

Microbadges

Nintendo DS fan
Nintendo DS fan