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 feature allows users to add more space for apps, photos, videos, and other files, making it easier to manage data without relying solely on the device's built-in storage. Common types of expandable memory include microSD cards, which can be inserted into compatible devices. This flexibility is particularly useful for users who need additional storage for large files or who frequently download new content, ensuring that they can keep their devices running smoothly without running out of space.