What is ISO?
An ISO is basically what your ASA used to be on your film.
The ISO is the sensitivity of your camera to the available light. So, if you are shooting in a place where it is very bright light, like at the beach or at the park and it is a bright sunny day, a 100 ISO suits.
If however you are going to be inside and maybe using your flash where there is not as much light, you maybe want it to be at something like 400 ISO
