Originally Posted by Reconde
I've gotten my answer on downgrading, could someone please explain to me what recovery is?
There's three ways you can boot your android device.
First is normal mode. That's the way it nomally boots, running the full operating system.
The second is downloader mode. This mode allows you to flash new software images using ODIN.
The third is recovery mode. Factory recovery allows you to flash updates, wipe the stock ROM, factory reset, etc. A custom recovery allows you to flash arbitrary updates (those which aren't signed by Samsung).
Phones running MDK bootloader can have a custom recovery that allows you to flash nonstandard ROMs.
Past MDK, this requires the use of Safestrap recovery.
My Android devices:
vzw Samsung Galaxy S4 stock NC5 rooted
Samsung Galaxy Tab 2 10.1, also stock but rooted.
VZ Droid Incredible 2 rooted but otherwise stock.
Samsung Galaxy Tab 10.1