Content is "portable" if you can read it easily on any device (it has portability), whether it's a large desktop screen or a tiny phone screen in the palm of your hand. Text should be comfortable to read, images should not be bigger than your screen, and all visible parts of the page should be fully functional, and in the right place.
Trying to read a page that was perfected for a large desktop screen on your phone can be very frustrating. If content was not designed with that type of use in mind, your smartphone screen will be bad at interpreting and displaying the page in a readable format. It is simply the wrong tool for the job - and with smartphones becoming more and more users' screen of choice, content needs to learn how to work with all devices.
What makes content portable?
Content is portable when it adapts to every screen - no matter its size or orientation. Whether you're looking at a page on your large desktop screen or scrolling down vertically on your small smartphone, the page should always be easy to read. To make that possible, images and page elements can move underneath or above text instead of sticking next to it, navigation bars may turn into dropdown menus, and some fun special effects may disappear on mobile, so your phone has no problems loading the page.
Why is this so important?
More than half of all visitors on Fandom come from a mobile device, such as a smartphone or tablet. While the number of desktop users has stayed roughly the same in the past few years, the number of mobile users has been steadily growing. In January 2015, their numbers surpassed our desktop users for the first time - and we expect the number of mobile users to keep growing.
Many pages on Fandom look perfect on desktop, but are very frustrating to read on mobile. We want to make sure they have the best possible user experience when they are looking at your pages, no matter what devices they're using.