As with most website navigation conventions, tabs are a tool that relies strongly on metaphor to work successfully. When used on a website, tabs should represent to the user the process of flicking through physical files or index cards. If this metaphor is not convincingly communicated to the user, their expectations of how the process will work will become confused, and they are likely to either misuse or not use this feature on your site.

Much has been written on how to appropriately implement tabs from a graphical aspect. Key rules include clearly highlighting the active tab, and visually linking the tabs to their content. However another important element of tab use, and one that is often overlooked, is how the information within the tabs is arranged and presented.

Jacob Nielsen recently published an article on the correct use of tabs (www.useit.com/alertbox/tabs.html). Much of what he discusses as key rules of tab usability have also been noticed in our own testing.

1. Users should not need to simultaneously view different tabs content. If users need to refer to more than one tab at a time, for example to make product comparisons or to enter information into a form, then consider presenting the information in a different format to remove their need to flick back and forth between tabs.
2. Tab labels should be short and indicate exactly what information the user can expect on that tab. Tabs represent an index of information, and are therefore likely to be scanned by users. It is unlikely a user will select every tab available to them, and if they are then perhaps tabs are not an appropriate way to present the information, you should consider a method that allows them to see everything they need without clicking on multiple tabs.
3. The range of information contained within the list of tabs should be immediately obvious to users. As with the previous point, users will perceive the list of tabs as an index, and need to know immediately whether the information they seek is contained within.

Essentially, the overarching rule of how to best manage information within your tabs is that the content of each tab should be the same information in a different context. Examples of this could be a weather report, with each state a tab, or a television program guide with each day assigned to a different tab.

A good rule of thumb when deciding whether to present your information in tabs is to think back to the old index cards we all remember from school libraries. If you cannot picture your information being easily found and used by flipping through cardboard cards in a box, then perhaps it is better to present your information in a different format.