Some users are unable to perceive colour differences, or may not perceive colour the same way you do. Therefore it is important to avoid using colour alone to communicate information. For example, if link text is blue, it should also be underlined so users who are unable to perceive colour differences can distinguish links from surrounding text.

Examples of this are usually found in buttons, links and navigation where we can be temped to suggest things like "click the button on the right of this page for accommodation information". It's not great at all for those who can't see where that button sits. It's always more beneficial to refer to the name of the component of the page you're referring to, for example "follow the more information on accommodation link, to learn about what's on offer at the University".