What Happens To The Deleted Data In Our System

Have u ever noticed what happens to the data u delete on Ur hard disk?
When we delete a file normally, it goes to the recycle bin and when we need the file again we can restore it.
But when we delete the file permanently and in case if u need the file again, what will u do?
Don't bother. U r not helpless.
We can even restore the files which we delete permanently.
What happens actually is when we delete a file the operating system does not delete the file from hard disk.
It just removes the link from the folder.
It still resides with in the system. The information about the deleted file and its contents are stored in a system folder called Recycler.
So when we need the file back we can use some specialized softwares like RECUVA and we can restore them.
But the worst case is , if there is no space in Ur hard disk during copying a new file into it, the data in the recycler is deleted for the new file to occupy its space.
This is the reason when we restore the file, we may not the get the complete contents of the file.