Find the File: How Computers Keep Track of Your Work

1 This section explains how a computer keeps thousands of files in order, how a path names the exact place a file is kept, and why a deleted file can usually still be brought back.

Folders Inside Folders

2 If a computer kept every file in one long list, every file would need a different name, and finding one would mean reading down the whole list. In 1965, two researchers working on a system called Multics, Robert Daley and Peter Neumann, described a better plan: a file system shaped like "a tree of files, some of which are directories," where a directory can hold other directories. Today most people call a directory a folder, after the paper folders in an office cabinet.

3 Folders inside folders form a tree. At the top is one starting place, such as This PC or My files. Inside it are a few large folders, such as Documents, Downloads and Pictures, and inside those are smaller folders that a person makes for each class or project. Two files can have the same name as long as they sit in different folders, because the computer tells them apart by where they are.

The Path to a File

4 The path is the list of folders that leads to a file, written from the outside in. On a school computer, the path Documents › School › English › essay-jones.docx means: open Documents, then the School folder inside it, then English inside that, and the essay is there. Some systems write the same path with slashes, as in /Documents/School/English, but the idea is the same: each name is one step further inside.

This PC
└─ Documents
   └─ School
      └─ English
         └─ essay-jones.docx

5 A path also explains the most common way people lose work. When a program saves a file, it puts the file in whatever folder is open in its save window. A student who clicks Save without reading that folder name may put an essay in Downloads instead of English, and later look for it in the wrong place. The file was never lost; it was saved somewhere the student did not choose on purpose.

A Second Chance

6 Deleting a file does not usually erase it right away. When Microsoft released Windows 95, the new features it listed included the Recycle Bin: a deleted file goes there first, and Restore puts it back in the exact folder it came from. A Mac does the same thing with the Trash. Apple's instructions say that items in the Trash "aren't deleted until you empty the Trash," and that File > Put Back returns an item to where it was.

7 Because a deleted file usually waits in the Recycle Bin, the first step after deleting the wrong file is to open the bin, not to panic. Emptying the bin is the step that cannot be undone: Apple warns that items emptied from the Trash "are permanently deleted and are no longer available." Careful users empty it only after they are sure nothing in it is needed.

When You Do Not Know the Path

8 As computers held more files, opening folders one at a time became too slow. Search tools, such as the search box in a file manager, look through every folder at once for names that contain the letters typed. A search result usually shows the file's path too, so a person learns both where the file is and where it should go. Search finds a file; the path tells you where it lives.

Sources: R. C. Daley and P. G. Neumann, "A General-Purpose File System for Secondary Storage," 1965 Fall Joint Computer Conference; Microsoft, "Launch of Windows 95"; Apple Support, "Delete files and folders on Mac."