Do you have a drive partitioned half NTFS and half OSX format just so can utilize the drive on both operating systems or resorted to the unreliable FAT or FAT32 for the convenience?
FAT was never designed to scale to the large storage systems available today. so modern operating systems evolved their own sophisticated file systems (Linux Ext3, Windows NTFS, & Mac HFS+) with various features to handle not only the enormously large capacities, but also provide fault tolerance among other valuable features. FAT, once ubiquitous, still survives today as the defacto file system for flash cards and USB drives. So why is a new file system called exFAT necessary?
It turns out, the modern file systems have significant overhead and are considered to be an overkill for flash drives -- some times making them slower.
exFAT (Extended FAT) was devised specifically to address these issues and more. Since the latest versions of Microsoft and Apple operating system support exFAT, it coincidentally serves as a great file system to interchange data between the operating systems too!
On OSX's Disk Utility application, you can easily select exFAT during the erase process and similarly on windows as shown:
In summary, exFAT borrows some valuable features modern file systems such as transactional file system TFAT among others. I'm personally using this as the filesystem for my external USB drive, however I did notice some applications on the Mac side, which rely specifically on Apple's HFS+ file system, are disabled. For example, I cannot move a Final Cut Pro X project to my external drive to work remotely -- it simply doesn't let me drop it there as it would an HFS+ partition.