Instead, operating systems only mark the space that was used by the deleted file as available for future files, because it is much faster to do. However, the content of the deleted file remains on the device until the operating system reuses the space for another file.
Modern operating systems can store a *journal*, a history of recent changes to the file system, or *snapshots*, an image of the file system at a particular point in time.
Flash memory devices, such as USB sticks and SSDs (Solid-State Drives), have *spare memory cells* that are used to replace broken memory cells over time.Modern hard disks also integrate small flash memories for performance and reliability.
To better protect from data recovery, you can use one or a combination of these mitigation techniques, depending on the sensitivity of your data and the risks.
By making it easy to avoid saving files to storage devices in the first place, using Tails is already an important mitigation technique given the limitations of file deletion.
Even if some data could still be recovered from [[spare memory cells|secure_deletion#spare]], overwriting the entire device is especially important if the device is not encrypted.
For top secret documents, the National Security Agency ([[!wikipedia NSA]]) of the USA recommends disintegration into particles of 2 mm. This can be achieved using a [good quality household blender](https://commons.erau.edu/jdfsl/vol16/iss2/1/).