The format word in computing means “defined arrangement of data encoded in a file or on a magnetic disk, essential for recording of data on different devices”,but most number of people still today believe format means erasing the data on a drive and making it completely refreshed to store data from scratch.
The statement above describing the definition of formatting means, arranging the disk in order to prepare the drive, so that it is able to manage data on a storage device, management of data includes storage, modification, deletion and data retrievability. Formatting a drive is a process, which arrives after creation of partition, which is mapping the drive to create user-defined regions. Such regions or partitions needs to be formatted before using them.
A logical drive or partition requires file system to manage data, when we format a drive a file system like FAT or NTFS in Windows takes control of the drive and creates its section and required files to manage data. Data storage on a drive is a complex form of a book having thousands of pages with big index at the beginning. A reader looking for a chapter locates the page number from the index and starts flipping pages to reach the chapter that he proposes to read.
Unlike book it is not that simple on a hard drive having millions of sectors, management of data becomes complex because mostly data never gets stored in a contiguous fashion. An index such as FAT or MFT is required to manage data or files.
This index or allocation information has the information about each sector or cluster (logical grouping of sectors) belonging to a file. Apart from recording the allocation information of a file, there is various other important information that needs to be managed by the file system such as folder or sub-folder management, file or folder attributes management (read only, hidden etc.), file security and log management (journal, bitmaps, quota and encryption). All these important file system components are required to manage your data and when we format the drive all these important attributes gets created again leaving all information about the data that is still available on a drive.
Therefore, once you format you clean your file system and instruct it to manage data again, wherein file system assumes the drive completely fresh and starts overwriting on those sectors, which still hold data. This is the reason why recovery is possible even after formatting a drive, recovery software apply special planned techniques and various algorithms, to find or create virtual pointers to those unlinked data.
Once the software is able to create a pointer it is as simple as copying data from one hard drive to another. The complexity increases with attempts of overwriting and fragmentation level, data once overwritten becomes unavailable for recovery, and there is no possibility to recover such data.
Here is how you can Recover accidentally formatted Hard Drive Data from Windows