RS-MMC, or Reduced Size MultiMediaCard, is a type of memory card used for storing data in portable devices. It is smaller than the standard MMC and is designed to fit into compact devices like mobile phones and digital cameras. RS-MMC cards can hold various amounts of data, making them versatile for different applications. Introduced in the early 2000s, RS-MMC cards were popular for their size and capacity. They often come with an adapter that allows them to be used in standard MMC slots. However, with the rise of newer formats like microSD, the use of RS-MMC has declined in recent years.