Which bit don't you understand Jani? if you set the exposure compensation on the meter - 1/3 your UNDER EXPOSING the image Wayne
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What does "under exposing" the image really mean? Yes, you are reducing the overall exposure. But given the dynamic range could well be larger than that of the sensor, you have to make choices. Calling it "under exposing" because you elect to not blow out your highlights is not accurate.
When dynamic range exceeds what the camera can handle, there are a number of options:
1) Use an ND grad filter (wow, this worked before digital!)
2) Manually throw some fill light on the foreground (works in a few cases)
3) Double expose and merge in photoshop
4) Expose for highlights and run through ACR or LR a couple times and merge in Photoshop
5) Multiple exposure and do HDR in Photoshop (or, better, Photomatix)
6) Expose for highlights and use "Fill Light" in LR or Shadows/Highlights in Aperture or Photoshop
... and probably others... we're not going to go into darkroom techniques like dodge/burn/building density in paper
But your comment about "under exposing the image" doesn't really make sense. What is "the image?" If you care most about the foreground, maybe a blown sky doesn't matter and you can expose properly for the foreground. If you care about the whole picture, you MUST retain enough detail in the sky... so use one of the above techniques. It's rare that you can take a landscape shot with *none* of these techniques and have every single piece of the frame exposed "exactly right." I mean, otherwise, Ansel Adams would have just made straight prints his entire life