Wikipedia
ExFAT
exFAT (Extended File Allocation Table) is a Microsoft file system optimized for flash memory such as USB flash drives and SD cards. It is proprietary and Microsoft owns patents on several elements of its design.
exFAT can be used where the NTFS file system is not a feasible solution (due to data structure overhead), yet the file size limit of the standard FAT32 file system is unacceptable.
exFAT has been adopted by the SD Card Association as the default file system for SDXC cards larger than 32 GiB.