I find on some projects I work on links are not clearly defined or standardized. It's not obvious to me and probably the end-user that links are links, or links may not be consistent across the application or even the same page. For example; some links are blue, some are green, some links are underlined, some links are not underlined.
It's important to define your links early on in your project – like before you write any code! The Guidelines for Visualizing Links will give you a great overview on the best direction for you to take in clearly defining and standardizing your links, but generally:
- Use one consistent color throughout your application.
- If possible choose a color that is generally recognized as a link, i.e. shades of blue, but this is not absolutely necessary.
- Use a second color to indicate that a link has been visited, e.g. purple.
- Provide visual cues such as underlines or titles.
- When making a title a link, provide an alternative link like "more" or "details", or in the least underline on hover.
- Borrow from the best.