flash tool is used to flash  or update your mobile. it help you to repair your dead android mobile. 

if your mobile is dead by mistake and you don't have any backup to revert all changes to repair your mobile then you dont need to worry about it. flash tool helps you to officially repair your mobile with USB cable without any cost.

these flash tools are used by service center to repair your mobile means if you update your mobile your self then its official not a pirated copy of your mobile's firmware.

every mobile have different firmware and different flashtool.

firmware is software version which contain all files of your mobile including IMEI no. software version, android version etc. and all other settings.

Flash tool for Micromax (SP tools)

Samsung flashing tool (Odin) download all files from the link

Karbonn mobile

LAVA mobile