title: Why is there a leading "#FF" in hexadecimal color values?
body: <p>I'm using <a href="https://en.wikipedia.org/wiki/Microsoft_Expression_Blend" rel="nofollow noreferrer">Expression Blend</a> 3 and am writing some of the XAML by hand, specifically the color values of controls.</p>
  <p>I have a list of RGB colors already converted to hexadecimal. I just need to insert the hex value into my XAML.</p>
  <p>Initially, I pasted the hex value from an email into the appropriate properties. Before I could finish, Blend started having a fit, underlining the color property with a squiggle and a tooltip telling me &quot;Token is not valid.&quot; After some research, I found placing a pound sign (&quot;#&quot;) in front of the hex value resolved this issue.</p>
  <p>In the process of researching this problem, I started changing colors via the color picker in Blend. I quickly found the values Blend was inserting not only started with the pound sign, but also &quot;FF&quot;. The values I was pasting were valid colors in a valid hex format. But when entering the RGB values into Blend and letting Blend insert the hex value, I noticed all my colors were prefixed with &quot;#FF&quot;. Removing the <code>#</code>, as I already pointed out, generated errors, but removing the &quot;FF&quot; seemed to have no effect at all.</p>
  <p>In the world of hexadecimal colors, is the color #5A7F39 really the same as <em>#FF5A7F39</em>? Why the <em>FF</em>? They are two different hex values, right? But they appear identical onscreen. Why the difference?</p>