Use of Color on a Webpage

Changing the colors of the text on a page is frequently done to add emphasis to a particular piece of text.  

i.e. "Don't miss the Important Deadline coming up"

Problems with using color in the text:

Visually impaired users using screen readers will miss the distinction in the color change entirely.  

i.e. "Don't miss the Important Deadline coming up"

And those users with a form of color-blindness may have the text de-emphasized instead.

i.e. "Don't miss the Important Deadline coming up"

It's also easy to get carried away with too much color and impact/distract sighted users.  

i.e. "Don't miss the Important Deadline coming up"

Or lose the text in the background if there isn't enough contrast:

i.e. "Don't miss the Important Deadline coming up"

The solution:

Instead of changing the color of the text, a better option is to rely on good use of the formats (Heading1, Heading2, Paragraph) for the text content on the page.  ÉðÊ¿Âþ»­ website uses a "stylesheet" (CSS) to control the colors and font sizes.  Setting this up globally makes for a consistent and easy to read website for everyone.

If you do need to emphasize some text...

Sparing use of the Bold and Italics setting can help draw attention to specific parts of the text - and these are recognized by screen readers.  Remember, though, that if you make everything Bold the emphasis is lost.  And don't use ALL CAPS BECAUSE IT LOOKS LIKE YOU ARE SHOUTING even if you don't mean to.  

When in doubt, keep it simple.