Your IMEI can be found at the back of your phone behind the battery or by pressing *#06# it is a 15 digit number.

Flash – This is the most common thing you modify on the phone.   The flash is essentially the operating system of the phone.   When you flash your phone it will adjust the various features of your phone.   You will not lose any of your media or any of your specific settings when you flash.   A flash can be used on most any carrier’s phone unlike the flex, which is carrier specific.   Reflash files are flash files.   They are called this I imagine because you use them to reflash a phone after you have already installed a monster pack on it but now you want the most recent flash.

Flex – These are the files that contain the cell phone service provider’s branding on the phone.   This is where things like your start up animation with the Cingular or T-Mobile logos and sounds come from.   It also contains the specific menus and labels for programs they use like T-Zones or MEdia Mall.   They also include all the programming needed to connect you to their Internet service and text messaging on their network.  The most important thing to remember is if you have a Cingular phone, then don’t install a T-Mobile flex on it. Your phone will essentially function, but any of the network connectivity for the Cingular network will be lost and you’ll need to reprogram the connection data specific to your carrier, or just flex again.

Monster Pack – Includes the flash and the flex and a language pack for a specific language all in one file.   It installs everything in one step. They come in many varieties, some are unbranded for Motorola, some are Cingular, O2, Rogers, and can come with various features already enabled.   Just read the description that the file comes with so you know what it does before installing it.

PDS – A 64kb section in memory that can’t be accessed via USB, unless you have bootloader “07.D0″ installed.   It holds critical information like your IMEI, ESN and any subsidy locking information.   The PDS is the most sensitive part of the ROM.   If it should become corrupted (downgrading when you shouldn’t, misuse of Flash Backup, etc.) you will need to use a Smart Clip or follow the test point procedures or get a copy of the free demo version of Motorola Repair Studio to fix it, otherwise your phone will be dead.

Seem – The phone has numerous seems programmed into the operating system of the phone.   These seems control every aspect of how the phone behaves such as: SMS being turned on or off by default, enabling the video camera and its various settings like zoom control and brightness of the image, raising the volume level on the various speakers of the phone, enabling ENS, etc.   You change one feature at a time when you edit seems in a hex editing program.   While the flash is all the programming on the phone, the seems edit the individual programs, if you will, in that flash, one feature at a time.