Generally, if we want to delete some file we just delete or want to permanent delete then in windows operating system we use Shift + Delete Button for permanent delete file.
When someone creates an image or video, maintaining the privacy of its content it is not as simple as “permanently delete” this information from the recycle bin.
Although it is removed from its original folder and trash, the file remains on the disk surface, so you can recover.
To illustrate what happens when a file is deleted, “You have to imagine a library with an index showing the location of each book states; in the case of computers and cell phones, when you delete a file, what you do it is delete index files of these devices.”
After a video is removed, for example, that instead of “index” is free, and rewrites use it only when necessary. Thus, the fact that a file ceases to exist when it is deleted is almost a matter of chance.
In turn, it can happen that only part of the content is clear, not entirely. “According to their weight, the files can occupy one or more blocks of information; when they occupy more than one, can happen that rewrites or reallocate only one or a few blocks, and not all of them, then part of the file can be recovered”
While those who believe that the only way to delete a file is destroying the hard disk of the computer or cell in which it is located, there are other ways to do it. “What makes the ‘wipe disk’ (or ‘Erase disc’) is rewriting its entire surface, so you make sure that no one can retrieve the information that was available”
Among the factors that can recover a deleted file, use the device in which it was stored has a significant weight. “If I delete a file from a computer today, I turn off the computer and turn on in three years, probably will be able to recover that information; however, if that computer has very active and used day by day and try to get the content after some day or even after tomorrow, then it will be difficult”
When we delete some unwanted files, its go to firstly trash bin, or according to your operating system like if you are using MAC then there is only trash, In Linux usually called the trash bin, and on windows its call Recycle Bin.
Just like physically Recycle Bin on our kitchen, and we throw something it not disappear immediately until its fill up and gets empty, when we do end up taking out the trash recovering your stuff.
But it could recover deleted data from computer system and phone, by recover tools to be used to recover, more advanced and the process is more complex, which makes them just a little safer.