Expandable memory refers to the ability of a device, such as a smartphone or tablet, to increase its storage capacity using external memory cards. This is often achieved through slots that accept microSD cards, allowing users to add more space for apps, photos, videos, and other files. Many devices come with a fixed amount of internal storage, which can fill up quickly. By using expandable memory, users can easily manage their data without needing to delete existing files or purchase a new device. This feature is particularly useful for those who store large amounts of media or run multiple applications simultaneously.