The R4 DS is a flashcart for the Nintendo DS or Nintendo DS Lite. A flashcart enables you to play games, which you can download from the internet, on your Nintendo DS for free.

Software

There are regular updates for the R4 DS card. These updates enhance the experience of the R4 DS. The updates are called 'firmwares'. The latest firmware is always downloadable for free at the offcial website of the R4 card:
Official website

The official website often is very slow. Because that, R4dscart.com offers a fast downloadlocation for the R4 firmware, version 1.18.
Download Firmware 1.18
You can upack the .rar file with Winrar.