Be careful when you use it or you could accidentally end up with an entire paragraph hyper linked instead of a short phrase. Imagine the traffic chaos if a town decided to use blue triangles instead of red octagons for their stop signs. Frustrated Web visitors will exit your site even more quickly. Links are your Web sites' signposts. They should give visitors easy visual clues to the site's navigation paths.
Most visitors have certain set expectations about links' look and function.
They may have problems with sites that don't conform to those expectations. Visitors expect links to be underlined. Never, ever use underlined text on your Web page. Underlining is an important visual cue of a hyperlink. If you need to emphasize text, use different text colors, bold, or italics - never underline it.