A memory card is a compact, solid-state electronic storage medium used to store digital information. Unlike a spinning hard drive, it uses flash memory—specifically NAND-based—which allows it to retain data without a power source and withstand physical movement. Primarily found in cameras, smartphones, and gaming consoles, these cards are defined by their form factor (such as SD, microSD, or CFexpress) and their speed classes, which determine how quickly they can “write” large files like 4K video or high-resolution RAW photos.