The Big Picture: Little Switches on Every File
Every file and folder carries a few on/off switches called attributes. They are stored in the file's $STANDARD_INFORMATION (Section 4.1). Each switch is a single bit. Some are hints to programs ("do not show this in the folder view"); others change how the file system stores the data ("squeeze this", "scramble this").
Attributes are not permissions. Permissions (Section 5) decide who may act. Attributes describe the file itself.
7.1 Read-only, Hidden, System, Archive
What it is: These four classic attributes go back to MS-DOS.
| Attribute | Short code | What it means |
|---|---|---|
| Read-only | R | Programs should not change or delete this file without clearing the switch first |
| Hidden | H | Explorer does not list it unless "Show hidden files" is on |
| System | S | Marks an important operating-system file. Explorer hides these even more strongly |
| Archive | A | "Changed since the last backup." Windows sets it whenever a file changes; some old backup tools clear it |
Important honesty about these switches:
- Hidden is not security. It only hides the file from the normal view. Anyone can show hidden files, and
dir /alists them. - Read-only is a polite request. It stops accidental changes in many programs, but you can clear it in two clicks. For real protection, use permissions (Section 5).
- The System flag is a warning sign: "this belongs to Windows".
On a folder, the Read-only box in Properties is mostly a marker used by Explorer (for special folders). It does not make the files inside read-only.
Change them in File Explorer: right-click the file → Properties → General tab → tick Read-only or Hidden. To see hidden files, use View → Show → Hidden items.
Change them on the command line with attrib:
attrib lists the attributes of files in this folder
attrib +r notes.txt set Read-only
attrib -r notes.txt clear Read-only
attrib +h notes.txt set Hidden
attrib -h notes.txt clear Hidden
dir /a:h list only hidden files
The letters in the output show what is on. For example:
A H C:\Users\Sam\Documents\FSLab\notes.txt
means the Archive and Hidden switches are on.
PowerShell: Get-ChildItem -Force shows hidden files too (-Force means "include things you would normally not see"). (Get-Item notes.txt).Attributes prints the switches as words.
7.2 Compression and Encryption Attributes (EFS)
What it is: Two more attributes ask NTFS to change how the data is stored. They only exist on NTFS.
Compression (C). NTFS can compress a file: it squeezes the data into fewer clusters, and unsqueezes it automatically whenever a program reads it. Programs never notice.
| Point | Detail |
|---|---|
| How to switch on | Right-click → Properties → Advanced → Compress contents to save disk space |
| How you can tell | Explorer can show compressed names in blue (a setting you may have to enable) |
| Cost | A little extra CPU time when reading and writing |
| Best for | Text, documents, logs. Photos, videos and ZIPs are already compressed and gain nothing |
Encryption (E) with EFS. EFS stands for Encrypting File System. Encryption means scrambling the data with a secret key so that it is unreadable without that key. EFS is built into NTFS and ties the key to your Windows account.
| Point | Detail |
|---|---|
| How to switch on | Properties → Advanced → Encrypt contents to secure data |
| What you see | The file works normally for you. Explorer can show encrypted names in green |
| Other users | Another account on the PC (even an administrator) cannot read the data without your key |
| Big warning | If you lose the encryption key (for example you reinstall Windows without a backup of the certificate), the data is gone for good |
| Availability | Not available in Windows Home editions. It is in Pro, Enterprise and Education |
EFS is not BitLocker. They solve different problems:
| EFS | BitLocker | |
|---|---|---|
| Protects | Individual files and folders | The whole volume (everything on the drive) |
| Tied to | Your Windows account | The drive, unlocked at start-up (for example by the PC's security chip, called the TPM, or a recovery key) |
| Guards against | Other users on the same PC | A stolen laptop or drive |
Windows Home often offers a simpler "Device encryption" instead; check Settings → Privacy & security.
Compression and encryption cannot be combined on the same file. If you turn on one, the other turns off.
Other attributes you may meet:
| Attribute | Meaning |
|---|---|
Not content indexed (I) | Windows Search should skip this file's contents when building its search index |
Offline (O) | Data is not stored locally (for example a cloud placeholder) |
| Temporary | A file meant to be short-lived |
| Sparse | A file with large empty stretches that do not use clusters |
| Reparse point | The file is a link or special item (Section 6) |
Seeing everything: In PowerShell, (Get-Item notes.txt).Attributes lists them all in words. In Properties → General → Advanced... you find "Index this file for faster searching" (the opposite of Not-content-indexed), compression and encryption.
Summary
| Term | Plain meaning |
|---|---|
| Attribute | An on/off switch stored with a file's metadata |
| Read-only (R) | Asks programs not to change the file; easy to clear |
| Hidden (H) | Not shown in normal folder views; not a security feature |
| System (S) | Marks an operating-system file |
| Archive (A) | "Changed since the last backup" marker |
| Compressed (C) | NTFS squeezes the data and unpacks it on read |
| Encrypted (E) | EFS scrambles the data using a key tied to your account |
| Not content indexed (I) | Skip the file's contents in Windows Search |
attrib | Command that shows and changes attributes |