ISO
ISO measures the sensitivity of the image sensor, the lower the number the less sensitive camera is to light and the finer the grain.
ISO which stands for international standards organization, is the light sensitivity rating of a digital image sensor .As you increases the ISO the sensor becomes more sensitive to light, which allows it to capture more light without slowing down the shutter speed or opening up your aperture.
Also means when how much light is coming in depending on the shutter speed and what auto is on.
(information from https://shuttermuse.com › what-is-iso-in-photography)
In my opinion my best photo is the first one is because the the light wasn't exposed showing you can see all the photo clearly. Also my worst photo is the last one because the the light was very exposed and can't see any of the picture .