The ISO … It’s a long story and it’s really meant to be related to the choice of the camera but rather how we take a photo which I’ll talk about later.
The ISO number on the camera is measuring the sensitivity of the sensor to light.
In some situations we need to have a low ISO (especially when we have light) and others we need to have it high (especially when it is dark).
Each camera has a maximum number for the ISO which if we go higher the photo will have noise and will be not clear.
This high ISO number is a thing we need to ask about when buying a camera. There is more than a site that have this information and you can look on the high ISO number of the camera you chose on those sites before you buy it.
Example of those sites is http://snapsort.com