Recovery Mode is a very important in Samsung phones and tablets. Through this mode, you can do the following tasks based on the type of recovery that you have (stock or custom recovery like CWM or TWRP).Stock Recovery:
Sometimes you may need to factory reset your phone for any reason including a fresh re-install of new stock or custom ROM, or you just want to make a factory reset before selling your phone or returning for warranty. Doing a factory reset in stock recovery ERASES EVERYTHING on your phone. However, doing a factory reset in CWM or TWRP does not, it only erases your settings/apps.
This Guide is about booting into download mode in most Samsung Phone/Tablets running Android OS. Download Mode can be used for the following tasks: