Exposure made simple...

Exposure refers to how light hits the sensor in your camera (and thus impacts the appearance of your pictures). There are three variables that determine exposure. I'll give you a summary here and just a bit more detail in separate posts.

Aperture
This setting is most often used to keep stuff up close in focus while the background is blurry (or out of focus). You often concentrate on aperture if you're taking portraits (to make the background blurry) or shooting landscapes (to keep things near and far in focus).

Shutter speed
This setting has to do with how long light is allowed to hit the sensor. It is typically measured in fractions of a second. Typically, the higher the number, the less time light is allowed to hit the sensor. In a bright environment, a high shutter speed keeps pictures from getting overexposed or "washed out".

ISO
This setting determines how sensitive the sensor is to light. A high number makes the sensor very sensitive. This may sound like a good thing, but can result in overexposed pictures and/or "grainy" pictures (pictures that look muddled, or unclear). The idea is to set the right sensitivity for a given set of conditions.