What concept is the residual representation of digital data that remains even after attempts have been made to remove or erase the data?

The concept you are referring to is known as "Data Residual" or "Data Remanence." Data residual refers to the remnants of digital data that continue to exist even after the data has been deleted or erased from a storage device. This residual data can remain on various media forms, such as hard drives, solid-state drives, or storage tapes, due to the way data is written and erased.

When data is deleted from a device, it is often merely marked as deleted in the file system. The actual bits of data may still exist on the storage medium until they are overwritten by new data. As such, individuals with the right tools can often recover this residual data, leading to potential security and privacy risks.

Preventative measures against data remanence include using data wiping software that employs methodologies like overwriting the data multiple times, or using physical destruction methods to ensure that the data cannot be recovered. This concept is particularly crucial in sectors that handle sensitive information, such as finance, health care, and government.