I suddenly notice an option called Secure Empty Trash. While Empty Trash is normally gotten by pressing Right Click on the Trash icon, for Secure Empty Trash, we have to only press Command button at that time.
I also notice that with Secure Empty Trash the System takes longer to empty the trash than normally. Why is that? What's the difference between them? And when should i use "Secure Empty Trash"?
Best Answer
This excerpt from Tech Republic explains it quite well (emphasis mine):
*This is incorrect. It's a 1X pass. See edit.
In comparison, "Empty trash" does not write over the 'deleted' data at all - it just marks the blocks where this data is stored on your HDD as available for use. It does not erase the actual data you discard.
Writing over a disk even one time takes a while. Simply telling the system "these blocks are now available to be written over" takes no time as well.
You should use "Secure Empty Trash" if you are deleting sensitive information and you want to make sure it won't be recovered in the future.
Edit:
That Tech Republic article is incorrect. As Andrew Medico correctly pointed out in his answer, securely emptying the trash performs a 1X pass. From Apple's Training Manual:
While the Erase Free Space option in Disk Utility offers 7X pass, the secure empty trash feature is only a 1X pass. Tech Republic seems to have conflated the two.