Photo Glossary - 01 - Exposure

I run a photographic club in my office and part of that is a contribution to the internal weekly bulletin.  At the moment I am using it to put together a photo glossary, which I will mirror here.
This is the first entry, originally posted in February 2011.
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Exposure
Exposure is the amount of light that falls on your camera’s sensor.  It affects how bright or dark your image is.  In a well exposed photo you can make out all the colour and brightness details across the entire picture.  In an over-exposed photo lighter areas will be ‘blown out’ to white and in an under-exposed photo darker areas will be “crushed” to black.

Your camera has 3 methods of controlling the exposure of a photo: shutter speed, aperture and ISO setting.