Question about Android Factory Reset

Hello members,

I'd like to ask a question related to factory reset option which is found in android mobile phones. If we factory reset android phone (Of course marking the "Erase Internal Storage" option, are there still some customization left or is it completely 100% returned to the condition like if its turned on for the first time. (Of course talking about software area, not hardware :P )

if you havent rooted, or flashed any themes and are on stock, then yes, it will return it to 95% original condition.

if any of the above, you may need to do a system wipe as well (just like format disk on pc) which will wipe off the os as well..

you just need to have a zip file of the fresh android you want to install present on an external sd card ready, or your phone will be blank.