In the FAT file system, directories are just special files, composed of 32-byte structures called directory entries. The topmost directory, the root directory, is located using information in the boot sector.
The normal (short file name) entries in this directory and all other directories follow the format shown in figure below (long file names are discussed a little further on in Short and Long File Names.
(1) Filename is the 8-character short file name (SFN). Eight bytes.
(2) File extension is the three-character file name extension. Three bytes
(3) File Attributes are the attributes of the entry, indicating whether it is a file or directory, writable or read-only and visible or hidden. One byte.
(4) Reserved area. One byte.
(5) Created Time (milliseconds) and is the fraction of the second of the date and time the file was created. One byte.
(6) Created Time is the hour, minute, and second the file was created. Two bytes.
(7) Created Date is the day, month, and year the file was created. Two bytes.
(8) Last Accessed Day is the day, month, and year the file was last accessed. Two byte.
(9) Extended Attribute Index. In FAT16, this field is used for extended attributes for some operating systems. In FAT32, this field contains the high two bytes of the cluster address. Two bytes.
(10) Last Modified Time is hour, minute, and second when the file was last modified. Two bytes.
(11) Last Modified Date is the day, month, and year when the file was last modified. Two bytes.
(12) Cluster address is the address of the first cluster allocated to the file (i.e., the first cluster that contains file data). In FAT16, this field contains the entire cluster address. In FAT32, this field contains the low two bytes of the cluster address. Two bytes.
(13) File Size is the size of the file, in octets. If the entry is a directory, this field is blank. Four bytes.