miniSD is a type of memory card that was designed to provide additional storage for portable devices like cameras, smartphones, and music players. It is smaller than the standard SD card, measuring just 20mm x 21.5mm, making it suitable for compact devices. Introduced in 2003, miniSD cards can hold various amounts of data, typically ranging from 32MB to 2GB. They are compatible with devices that support SD and SDHC formats when used with an adapter, allowing for greater flexibility in storage options.