00:00Have you ever deleted a file and thought it was gone forever?
00:03You might be surprised to learn that your computer is actually lying to you about those
00:07files being destroyed.
00:09Once you click delete and empty that trash bin, your files are often still right there,
00:13hiding in plain sight on your drive.
00:15You probably want to know what actually happens the moment you click that delete button.
00:19Well, think of your computer storage like a massive library.
00:22Once you delete a file, the computer doesn't not run into the back room and burn the book
00:26immediately.
00:27Instead, it just walks over to the library catalog and rips out the little index card
00:31that tells you where the book is on the shelf.
00:33The book is still sitting right there on the shelf.
00:35But because the index is gone, the operating system just pretend it does not exist.
00:39You might ask if the file is still there, then where does it go in the computer's memory?
00:44The computer simply marks that specific area on your hard drive as available space.
00:48It tells the system that it is now okay to write new information over that exact spot
00:52whenever it needs more room.
00:54This leads to another big question, can someone else actually find my deleted files?
00:58Yes, they absolutely can, if the data has not been replaced yet.
01:02Since the data is still physically on the test, specialized recovery software can ignore the
01:06broken index and scan the drive to find those ghost files.
01:09This is why simply hitting delete is not enough to protect your secrets if you are getting rid
01:13of an old laptop or phone, so when is a file actually truly gone for good?
01:17A file is only destroyed when new data is physically written over the exact same physical
01:21space on the drive.
01:22This process is called overwriting, and it is like taking that library book off the shelf
01:27and writing a brand new story on top of every single page.
01:30But why does the computer choose to do?
01:31It is this way instead of just erasing it immediately.
01:34The simple answer is speed, erasing the actual data by overwriting it takes a long time, almost
01:39as long as it takes to save the file in the first place.
01:42For example, if you delete a huge movie file, removing the index card is nearly instant, but
01:47actually erasing every single bit of data could take several minutes.
01:50Computers choose the first way so you are not stuck waiting every time you try to clean
01:54up your desktop.
01:54Now you might wonder if it matters what kind of computer or storage device you are using.
01:59It actually makes a huge difference in how long your deleted data stays alive.
02:02If you have an old-school hard drive with spinning disk, those files can stay in that good state
02:07for a long time, until you save enough new files to eventually overwrite them.
02:11However, if you use a modern storage state drive, there is a special command called trim
02:15that changes everything.
02:17Trim tells the SSD to clean up that deleted data during the computer's downtime so it stays
02:21fast, which means your deleted files on an SSD usually disappears much quicker than
02:26on a regular hard drive.
02:27Does emptying the recycle bin or trash make a big difference?
02:30Not as much as you might think.
02:32The recycle bin is just a safety net folder that holds your file, so you can change your
02:36mind if you made a mistake.
02:37Once you emptied it, the computer finally performed that intact sleeping trick we talked about earlier,
02:42but remember the data is still sitting there in the background, until something else takes
02:46its place.
02:47If you really want to make sure a sensitive file is worn forever, you need to use secure
02:51erasured software that overrides the data with random junk multiple times.
03:13systems.
03:14You
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