ISO is your camera’s sensitivity to light, with a typical range of 100-1600. Some cameras can go as low as 50 or 64, and reach as high as 12,600, but these are found in very expensive camera bodies. ISO settings are best used in manual mode, but it can be placed on Automatic on Canon cameras I got this information from https://photographylife.com/what-is-iso-in-photography
Best picture In my opinion this is my best picture that i took because the background is blurry and the object in the front was clear and prefect Another point the lighting was good.
Worst picture in my opinion i think this is the worst picture i took because the background is all black and you cant see the object probably
My understanding I understand how to use ISO setting like i know when the picture is dark and i check the iso just to make sure if it's a good setting or not