Data wiping uses certified software to overwrite stored data, making it unrecoverable — best for HDDs that will be reused or redeployed. Degaussing exposes media to a high-intensity magnetic field, erasing all data and rendering the device unusable — best for highly sensitive HDDs. Shredding physically destroys the device into small pieces — best for devices that must be completely destroyed, including SSDs, paper, and mixed media.