Odin is a utility software program developed and used by Samsung internally which is used to communicate with Samsung devices in Odin mode (also called download mode) through the Thor (protocol). It can be used to flash a custom recovery firmware image (as opposed to the stock recovery firmware image) to a Samsung Android device. Odin is also used for unbricking certain Android devices.[2] Odin is the Samsung proprietary alternative to Fastboot.
There is no account of Samsung ever having officially openly released Odin,[3] though it is mentioned in the developer documents for Samsung KnoxSDK[4] and some documents even instruct users to use Odin.[5] Some other docs on KnoxSDK reference "engineering firmware",[6][7] which presumably can be a part of the KnoxSDK along with Odin. Publicly available binaries are believed to be the result of leaks. The tool is not intended for end-users, but for Samsung's own personnel and approved repair centers.[8]
For the usage of Odin, the phone needs to be in Download mode. For this, some key combination need to be pressed, such as Power + Volume Down + Home, or Power + Volume Down + Bixby for later models.[9]