ISO International Standards Organisation

The ISO (International Organization for Standardization) give state of the art specifications for products, services and good practice. This helps the industry by making things more efficient and effective. 
ISO were founded in 1947 and since then have published over 19,500 international standards covering all aspects from technology and also business, food safety, computers, agriculture and health care. It impacts all our lives.
This is a picture of the founders of the ISO pictured in London in 1946:

This is a picture of a high ISO vs low ISO using a DLSR camera:

By looking at both pictures you can see that there is a massive difference, the low ISO of 100 is completely different, it is blurry and fairly unclear, which doesn't really attract anyone to want to look at the photograph. Where as the high ISO of 800 is so much more clear on the main subject. The background is still fairly blurry but the photograph looks a lot better and attracts the audience a lot more.

ISO is the level of sensitivity your camera is available to light. The lower the ISO number the less sensitive your camera is to light, whereas the higher the ISO number it increases the sensitivity of your camera which creates a lot better of a photograph.