ISO is one of three factors which determine the exposure of a photo, along with aperture and shutter speed. To really get the most out of your photos you need to know what all 3 do and how you can use them. Read this post to gain a more in depth knowledge of how to use your camera properly and start taking expert photos.
General Rules and tips for ISO Camera Settings: •Use an ISO of 100 or 200 when taking photographs outside in sunny conditions. • If the sky is overcast or it is evening time, then use an ISO within the range of 400 to 800. • Night time or in cases of low light you might need to set your digital camera ISO to 1600. If you don't then your photo will appear too dark if at all.