Let me first apologize as I know this topic appears to have been discussed extensively yet something isn't clicking for me after researching over many days in stack, google, and youtube! I want to clarify a few thoughts in my head on the applicability of anti-static devices (such as wrist straps and mats) and how they work. I'll list my current thoughts/questions as follows...
1.) The purpose of the resistor in the strap/mat grounding cable: As I understand it the purpose of the resistor is that when there is a potential difference between you and the device you are working on the resistor will limit the current fed into the device to reduce damage. Is this true?
2.) How ESD occurs when working on a device: I understand that ESD occurs when there is a voltage difference between you and the device. I also understand that voltage is a relative measurement between two points. Additionally I've been taught that "ground" and "earth ground" are two different things. My big source of confusion is how you prevent an initial static discharge. As I understand when we are connected to "ground" it is not necessarily earth ground. This "ground" potential can vary depending on the electricity provider. As such, wherever your device is developed will have achieved equilibration in charge relative to whatever "ground" it was prepared relative to (assuming manufacturers develop devices by grounding themselves and all components). Where I am getting mixed up is that say when I take out a computer motherboard (which will be at a certain potential) and put it on an anti-static mat and connect the mat to my local ground source, isn't there still a possibility that very act may lead to a voltage difference (due to different relative "grounds" and cause an initial discharge? Or is the variability in what is considered "ground" standard throughout the U.S?
3.) When working with devices is it best to connect everything to ground? Or do you connect everything to the device? As I understand it you either set yourself and your device to ground potential or you set your-self to the same potential as the device. In both cases wouldn't there still be an initial discharge? A scenario in my head is that I touch the bare metal of a grounded outlet to disperse any static on me initially. When I go to handle the device how can I be sure that the device is at the same grounded potential within its anti-static packaging and that I won't discharge current through it?
4.) Assuming that there is a natural inevitable discharge and that my concern about that is correct, is it just a matter of which is safer, the "natural" discharge or the ESD? As I understand ESD can lead to a potential difference of hundreds to thousands of volts. If I use a CPU as an example device I believe anything over 2-volts has the potential to damage/fry the CPU. In this case ESD is definitely bad news. However, due to just transportation across the U.S and the potential of difference of relative grounds is it likely that there is always a few volt difference between me and anything else that I interact with? In this case, wouldn't I potentially always damage the CPU when removing it from its packaging?
5.) Lastly, as I see it now with all my concerns, ESD devices such as wrist straps and mats do not protect you and your device against any initial discharge (since there may always be a difference in your resting potential), they only prevent the future build-up of static as you are working on the device. Is this true?
Thank you very much for your patience in helping me figure this out!