FAT: A file allocation table (FAT) is a file system developed for hard drives that originally used 12 or 16 bits for each cluster entry into the file allocation table.

It is used by the operating system (OS) to manage files on hard drives and other computer systems. This includes DOS and all early versions of Windows, beginning with 3.x through Windows 98 Second Edition. Actually, Windows NT through Windows XP uses FAT as well, but only under certain circumstances.

OS X: এটি mac OS এর এক ধরনের Disk Format.

NTFS: New Technology File System. It is a file system developed by Microsoft. Starting with Windows NT 3.1, it is the default file system of the Windows NT family.

EXT2: Second Extended File System is a file system for the Linux Kernel.

আপাতদৃষ্টিতে FAT এবং NTFS একই Operating System এ ব্যবহার করা যায় - এরকম মনে হতে পারে। প্রকৃতপক্ষে FAT, NTFS এর Predecessor বা পূর্বসূরী। তাই MS DOS 6.0 এর ক্ষেত্রে উত্তর হবে FAT System. ।