Flash File is required to flash the tablet. If in any case your Mobile or Tablet get stuck at android logo or if you had forget password & hard reset is not working then you have to install the OS again. The download package include Flash tool required to perform flashing. Below here the different mobile brand is listed. Check out your brand and download the ROM for your mobile.
Flash File in mobile is Operating System software that manages Mobile hardware and Software services which provides common services for Mobile programs.
Flash File in Android is just like Operating system in PC which manages hardware & Software services for the Phone.