Understanding ISO

What is ISO? 

ISO is the measure of a digital camera sensors sensitivity to light.

ISO is seen as grainy when it is a high ISO, and when it;s low its clear.

It is in relationship with the exposure triangle.

 ~Low ISO~                                                        

 Aperture-f/3.5

 ISO-100                                                               

Shutter Speed-2.0                                                        

~High ISO~
Aperture-f/3.5
ISO-6400
Shutter Speed-1/40