An SD card is a removable flash storage card used in cameras, embedded systems, portable devices, and other equipment that needs compact local storage. It can hold photos, logs, firmware, configuration files, and other data that a device must read or write without a fixed disk.
In cyber security, SD cards matter because they are easy to remove, clone, tamper with, or replace. Attackers may use them to move data, introduce malicious firmware, or persist changes in unattended hardware. Defenders and repair teams also rely on them for forensics and incident response, so a card that will not mount should be checked carefully for power, connector, and controller faults before assuming the data is lost. Secure handling, write protection, and imaging before modification help reduce risk.