The Big Picture: Many Systems, Different Strengths
There is no single "file system". There are several, and each is a different set of rules for organizing the same raw blocks. Think of different filing styles for the same warehouse: a simple label-and-shelf scheme, or a full library catalogue with locks and an audit log. Windows can use four main ones. They differ in features, limits and who can read them (Windows, Mac, Linux, cameras, TVs).
Here is the quick comparison. Each one is explained below.
| FAT32 | exFAT | NTFS | ReFS | |
|---|---|---|---|---|
| Typical use | Old drives, small USB sticks, camera cards, boot partitions | Big USB drives and SD cards | Windows system drive and most internal drives | Servers, special drives |
| Biggest single file | 4 GB minus 1 byte | Huge (far beyond any real file) | Huge | Huge |
| Permissions (ACLs) | No | No | Yes | Yes |
| Journaling (crash recovery log) | No | No | Yes | Uses a different method |
| Compression, encryption (EFS) | No | No | Yes | Not the NTFS kind |
| Works on Mac and Linux | Yes | Yes (modern versions) | Mac reads only; Linux can read and write with extra software | Windows only, in practice |
2.1 NTFS (Modern Windows Default)
What it is: NTFS stands for New Technology File System. It arrived with Windows NT in 1993 and is still the standard file system for Windows 10 and 11. If you installed Windows, your C: drive is almost certainly NTFS.
What it can do:
| Feature | Plain meaning |
|---|---|
| Journaling | Keeps a log of changes, so a power cut does not leave the file system broken (Section 4.4) |
| Permissions (ACLs) | Controls exactly who can read, change or run each file (Section 5) |
| Compression | Squeezes files to save space; Windows unpacks them automatically when read (Section 7) |
| Encryption (EFS) | Scrambles a file so only your account can read it (Section 7) |
| Hard links and junctions | Give one file or folder several names or entry points (Section 6) |
| Alternate data streams | Extra hidden data "attached" to a file's name (Section 3.3) |
| Very large files and volumes | Limits far beyond anything normal |
| Long names | Each name part can be up to 255 characters, in Unicode (so any language works) |
How it stores things: Everything, even the file system's own bookkeeping, is stored as files. The key structure is the Master File Table, a big table with one entry per file. Section 4 opens it up.
Windows tip: Right-click the C: drive in File Explorer, choose Properties, and read File system: on the General tab.
2.2 FAT32 (Legacy, Simple, Used for Compatibility)
What it is: FAT stands for File Allocation Table. It is a very old, very simple design from the days of MS-DOS. FAT32 is its 32-bit version from the late 1990s. The "table" is a long list with one slot per cluster, and each slot says "the next cluster of this file is number X". A file is therefore a chain of clusters, like a treasure hunt where each clue points to the next.
The FAT (the table), one slot per cluster:
cluster: 5 6 7 8 9
slot says: 9 - - - END
File "Song" starts at cluster 5.
Follow the slots: 5 ──► 9 ──► END (Song uses clusters 5 and 9)
Strengths: It is simple and works almost everywhere: Windows, Mac, Linux, game consoles, TVs, cameras, and the small boot partition that UEFI firmware reads (Chapter 5 covers boot).
Limits:
| Limit | Meaning |
|---|---|
| 4 GB file limit | No single file can be 4 GB or bigger (the limit is 4 GB minus 1 byte). A large movie or disk image will not fit. |
| No permissions | Anyone who can plug in the drive can read everything. |
| No journaling | Unplug it carelessly mid-write and files can be damaged. |
| Volume size | Larger volumes are possible in theory, but the built-in Windows format tool only offers FAT32 for smaller drives (around 32 GB). Other tools can format bigger ones. |
When to use it: Small USB sticks that must work in old devices, and boot partitions. For almost anything else, pick exFAT or NTFS.
2.3 exFAT (Modern, Cross-Platform, for Flash Drives)
What it is: exFAT (extended FAT) was made by Microsoft to fix FAT32's biggest problem, for flash storage such as USB sticks and SD cards. It keeps the "simple and widely supported" spirit but allows very large files and drives.
| Feature | exFAT |
|---|---|
| File size limit | Practically none (far above FAT32's 4 GB) |
| Permissions | No |
| Journaling | No (so remove the drive using "Safely Remove Hardware") |
| Support | Windows, modern macOS, Linux, many cameras and consoles |
Typical use: Large SD cards in cameras (they are often formatted exFAT), and big USB drives you move between a PC and a Mac. It is the best "carry it anywhere" choice when you need files over 4 GB.
2.4 ReFS (Resilient File System, Server/Enterprise)
What it is: ReFS is Microsoft's newer file system built for resilience: surviving and repairing damage, especially bit rot (data silently going wrong over time). It was designed for servers and big storage pools. It uses checksums (a small fingerprint number per block) so it can notice when data has changed by mistake, and with a mirrored copy it can repair it.
Where you may meet it:
- Windows Server and storage built from many disks (Storage Spaces).
- Dev Drive, a Windows 11 feature for developers that is built on ReFS to speed up build work. (Availability depends on your Windows version, so check your own PC rather than assuming.)
How it differs from NTFS: ReFS gives up some NTFS features (for example NTFS compression and EFS encryption) in exchange for strong integrity checking and very large scale. Windows is normally installed on NTFS, not ReFS. Treat ReFS as a specialist tool for now.
2.5 Other Systems You May Hear About
One line each, for context only. Windows does not use these natively:
- ext4 is the common default on Linux.
- APFS is what modern Macs and iPhones use.
A Windows PC cannot read them without extra software, which is why USB sticks you want to share use FAT32 or exFAT.
2.6 How to Choose
Need a Windows system or main drive? ───────────► NTFS
Need files over 4 GB on a stick for PC + Mac? ──► exFAT
Need maximum compatibility with old devices? ───► FAT32 (files under 4 GB)
Running a server with a big storage pool? ──────► consider ReFS
Windows tip: To see the type of every volume, open PowerShell and run Get-Volume. The FileSystem column shows NTFS, FAT32, exFAT or ReFS.
Summary
| Term | Plain meaning |
|---|---|
| NTFS | Full-featured Windows default: journaling, permissions, compression, encryption |
| FAT32 | Old and simple, works everywhere, 4 GB file limit, no permissions |
| exFAT | FAT without the 4 GB limit, for USB sticks and SD cards, no permissions |
| ReFS | Newer, checksum-based, for servers and special drives such as Dev Drive |
| ext4 / APFS | Linux and Apple file systems (one-line mention) |