title: Color Blending vs Alpha Blending
body: <p>While experimenting with the XNA BlendState class, I found that it has <strong>two</strong> state groupings:<br>
  One for <strong>Alpha Blending</strong> and one for <strong>Color Blending</strong> (as the framework calls it).</p>
  
  <p>The mutable members of each group are termed <code>*BlendFunction</code>, <code>*DestinationBlend</code>, and *SourceBlend<br>
  (where <code>*</code> is replaced by either <code>Alpha</code> or <code>Color</code>).</p>
  
  <p>I understand how to blend two RGBA colors, and  I assume that's what the Color Blending function are for</p>
  
  <hr>
  
  <p><strong>What's the purpose of this 'alpha blending' that XNA apparently supports? How does it work?</strong></p>
  
  <p><strong>Aren't all 4 color components, including the alpha value, modified by Color Blending anyway?</strong> </p>