It feels like I am having difficulty discerning GBP when it comes to open and closed loops and feedback. The literature and videos I've found to try and understand this better don't really explain the differences (specifically) and it feels like its being used interchangeably (Obviously it's not; but as a student new to the material it feels that way). Here is my current understanding and PLEASE correct me where I am wrong (This is all in my own words):

In an open loop configuration, an "ideal" amplifier has an unbounded gain potential because there is nothing holding it in check without a feedback loop. A closed loop configuration attempts to curtail this with a resistor network, with a negative feedback driving any observable error to zero and a positive feedback amplifying that error. In term of gain bandwidth product, this is the linear relationship of the frequency response of an amplifier between the -3 dB break frequency, and the 0 dB cutoff frequency (or unity gain, where the input would match the output). It is along this slope that the decibel value along the y-axis of the bode plot and the frequency value along the x-axis would equal the cutoff frequency, no matter where along that line they are selected.

__In an open loop response, this GBP relationship would not exist because the bode plot would just be a straight line that goes on forever. In a closed loop response, the GBP does not appear until the -3 dB break, and would just be the open loop straight line until that point.__

The biggest point of confusion is in those last two lines that I have underlined. I will read or watch one thing where they are talking about GBP with an open loop and another thing where they talk about GBP with a closed loop. At an additional request, this is more so just for my own understanding, but what practicality does an open loop offer? Is it just to see what an unrestricted performance that particular amplifier can provide?

Thank you in advance for any assistance. I always like to bounce my knowledge

*as I understand it*with someone who does to see where any faults may lie.