Adjustable Metering Modes

You may have come across “Metering Modes” whilst reading through your camera’s operator’s manual and thought at the time, ‘That sounds a bit technical, I think I’ll leave that one alone.’
“What does it all have to do with anyway?” You might ask.
Well basically, the in-built “light metering” system in your camera takes a reading from different areas of a scene and then determines a correct exposure from that reading. And hopefully, you will not end up with a photo that is too light or too dark.
Most DSLR cameras today, and even some new point and shoot digital cameras, come with a user friendly, adaptable metering system and these things are made adaptable for good reason. It’s not as though you are treading a mine field, expecting the camera to blow up if you try out the different modes to see how they affect different exposures. And they really are - user friendly!
It is just another thing you need to be concerned about when composing your shots. You really need to assess the brightness levels of a scene and act accordingly. Anyway, isn’t it good to know there is something else we can have a certain amount of control over?
So, if you have manually adjustable metering modes on your camera, the following are the three metering modes that you are likely to have, but not necessarily in this order:
First, we shall discuss the “Spot” Metering Mode.With the camera set on this mode, whatever there is in the small area, directly in the centre of frame, will be metered for.
This is very handy for when you want to take a meter reading for a certain area in the scene. Such as an overly bright area or a particularly dark area. If you did not meter for these areas, chances are they will be either washed out or silhouetted. 
Also, when you are photographing a sunset or sunrise, you will get a more favourable exposure if you meter for the brightest part of the sky, but not the sun itself. Simply aim the camera at the area in question, depress the shutter half way to get a reading, make a note of that reading, then go into manual mode, set the new reading ( shutter speed and aperture setting) into the camera and recompose the shot.Second is “Centre Weighted” Mode.In this mode the camera takes into consideration a much wider area than the spot meter. It will take readings from numerous other points, but is still more concerned with the centrally weighted area of the frame.
As with the spot meter, it is handy for when you need to get a special reading from a certain area other than throughout the scene.
Last, is the “Multi Segmented” Mode.
This is generally the default setting on most cameras and it meters for the entire range of the frame. One camera I know has up to 35 metering points in the frame.
Most people tend to keep their camera set on this mode without ever thinking, at times they may need to adjust it. I prefer actually to keep mine on the centrally weighted mode, but I am ready to change that if I feel the need arises. Especially after assessing the brightness levels of a scene or of the subject I am photographing.