Exposure- Exposed

When correctly exposed, a photograph will have an entire spectrum of values
Highlights ... Shadows ... Medium values

image by Ansel Adams, a master of exposure.

THE ZONE SYSTEM

Ansel Adams, along with Fred Archer, formulated a technique which they termed the Zone System. It is a method which assists the photographer in calculating the most precise exposure to any given circumstance.
A photographer knows the difference between freshly fallen snow and a black horse, while a meter does not.
The Zone System assigns numbers from 0 through 10 to different brightness values, with 0 representing black, 5 middle gray, and 10 pure white; these values are known as zones. (source: Wikipedia)

Your internal camera meter renders the middle value/tone of the over all image. This is another reason (besides white balance) why I recommended you all obtain a gray card. Have you ever taken a picture of a person in all black or in all white and the photo turned out to be too light or too dark? This is because your camera keyed into the light reflecting off the the black (or white) and rendered it as medium gray instead of black (or white).
The Zone System provides a straightforward method for rendering these objects as the photographer (YOU) desires, and not as the internal camera meter dictates.
Using your gray card, you can guarantee that you’ll have each value fall where it should (either on the shadow end or the highlight end).
Place your gray card in front of your subject, with the same amount of light falling on it as your subject. Now use your gray card to determine the correct exposure for your photo- keeping an eye on the internal light meter in your camera. Your gray card will help you obtain the correct combination of your shutter speed and aperture for the image to be accurately exposed. At this point, you can take one picture with the gray card still in the image for post-processing white balance customization. And now, having your exposure set you can start shooting. If, at any point, your light source or direction/amount of light changes, you'll want to revisit your exposure and meter again so that you're accurately exposing every frame.

Suggested workflow:
Set your ISO
Choose your meter mode (you can adjust this, refer to your user manual or use google to figure out how to make these specific adjustments on your camera). I recommend using the "spot meter" mode.
Set your camera to “M” mode
Place your gray card in your scene facing the lens
Take a meter reading by pressing the shutter button halfway
Pay attention to the internal meter reading, adjust your camera so that the exposure bar is in the middle
Compose your subject, making sure that your exposure adjustments haven’t changed
Focus and take the picture
Take one version of the photo with the gray card in it (for accurate white balance readings) and another without the gray card

Key Terms
Underexposure: Too little light or too dark
Overexposure: Too much light, washed out, too light

REMEMBER: You will always get the best results if you start off by making an accurate exposure!!!

Now that you have the necessary tools, you can begin to manipulate scenes to achieve various results that shooting on “auto” wouldn’t give you. You can use your knowledge of metering, shutter speed, aperture, ISO, and white balance etc to be able to render a mood to your photographs that you wouldn’t have been able to other wise. This is the part where photography can start to be super expressive and fun. Where you will begin to see light and will begin to capture it according to your artistic vision!!