Some time ago, I ran across an interesting post on Clients from Hell:
Website user who couldn’t find an article emailed our help desk. We sent him the link to the content he couldn’t find.
Client: “Please change the letters in your email to blue, so I can click the link.”
While this was intended to ridicule a misunderstanding — that the client couldn’t click the link unless the letters were blue — it does stand to illustrate a real problem with usability. Even though there may be relatively few people who actually experience the exact problem above, there are undoubtedly many people who could fail to realize that text is a link when it doesn’t conform to their expectations.
It’s not just whether or not your links are blue — there’s also an issue with internal consistency. If you’ve made a decision that links will be something other than blue, people can learn that. But you may want to consider being internally consistent with that change — I’ve seen many web sites where different areas of the page change the coloration of links: sidebar links are gray, body links orange, footer links black, etc.
Regions of the page specifically dedicated to navigation can frequently get away with alternate appearances, but having a different link scheme all around the site is very likely to just confuse. Inconsistent coloration, inconsistent use of text underlining, or minimal hover or focus changes can all serve to reduce the usability of your web site in significant ways.
Do links need to be blue? No, not really. If you insist on always having links blue you’re going to limit your design options in more ways than are really likely to be beneficial. However, if blue links won’t compromise the design, there’s really no reason not to use them.
Keeping basic usability in mind at every stage of design is just a good idea — at least, if you’re going for a successful web site!