How does an R4 card work?

An R4 card is a type of flash memory card used primarily in Nintendo DS and DSi consoles to play games and run homebrew applications. It functions by allowing users to load game files onto a microSD card, which is then inserted into the R4 card. The R4 card acts as an intermediary, enabling the console to read the game files stored on the microSD. This setup allows for easy access to multiple games without needing to switch physical cartridges.