You want to let the site's presentation of content fit the specific needs of the user.
Provide a mechanism to switch or alter the default style of a page so that it fits the specific needs of the user.
When catering to alternative browsers such as mobile phone browsers, the view to present can often be found looking at the incoming user agent. In this case, a manual mechanism to switch styles might seem obsolete, but it is good practice to allow access to all views of a site regardless of how the user is browsing it.
Provide a manual control to allow users to switch/alter the default style of a page so that it better fits their specific needs. It is for instance not all iPhone users who actually like to use tailored iPhone versions of websites instead of the full-featured browser version.
It is a good practice to allow for permanence of the user’s preferred configuration. This will prevent the user from having to make the same adjustment each time a page reloads.
By providing a mechanism to present different views of content to the user, you can tailor usability and the experience you want to give your users to their specific needs.
This and others patterns are available and ready to use in this massive Wireframe Bundle. Suitable for a wide variety of projects: Website and landing pages, Ecommerce, Dashboard, Flowchart and iOS.