Wirebook › Lesson 8 of 18
Where do deleted files and photos go?
You delete a photo, empty the bin, and it's gone. Or is it? Usually the computer doesn't rub anything out at all: it just forgets where the file was. Here's a tiny pretend disk so you can watch exactly what happens, and then we'll follow the copies that live in the cloud.
Deleting is mostly forgetting
Rubbing out every bit of a big file would take time, so computers take a shortcut. When you empty the bin, the file system (the part that keeps the file table) simply crosses the file off its list and marks its blocks as free to reuse. The ones and zeros of your photo are still sitting there, untouched, until something new happens to be saved on top of them.
That's why recovery programs can sometimes bring back deleted files: they skip the file table and read the raw blocks, looking for things that look like photos or documents. It works best soon after deleting, before new files have overwritten the space. Try it above: empty the bin, then save a few new files and watch the detective's chances shrink.
The bin is a second chance, not a shredder
Pressing delete first moves a file to the bin (or the Recently deleted album on a phone). Nothing on the disk changes; the file just moves to a different list, which is why "restore" is instant. Many phones and apps empty that bin by themselves after about a month.
Phones, SSDs and encryption make "gone" more gone
- SSDs tidy up. The flash memory in phones and most new laptops can't write over old data directly; it has to erase it first. So the computer tells the drive which blocks are free (a command called TRIM) and the drive wipes them in the background, often within minutes. After that, there's nothing left to recover. Press SSD tidy-up above to see it.
- Encryption scrambles everything. Modern phones encrypt their storage. Leftover blocks are just scrambled nonsense without the phone's key, and when you reset a phone it can simply throw the key away, which makes all the old data unreadable in an instant.
- Shredding overwrites. "Secure delete" tools write zeros or random data over a file's blocks before forgetting it. On old spinning hard drives, one full overwrite is enough.
What this means for you
- Deleted by mistake? Look in the bin or Recently deleted album first, then the cloud's bin. Act quickly and save nothing new on that device.
- Selling or giving away a phone or laptop? Use its built-in "erase all content" or factory reset. On modern encrypted devices that throws away the key, so the old data can't be read.
- Think before you send. A copy you've shared can't be pulled back. That's the one delete button nobody has.
Related lesson: is my hard drive getting old? Read its health chart with Grandpa Spinner.