Navigation

Requirements

• Limit scrolling to one direction unless users cannot avoid secondary scrolling, or it aids the overall experience for more than one user group. For example, a carousel will require a horizontal swipe gesture. However, this may require a control/ button for mobility-impaired users or an Accessibility hint for screen reader users.
• Ensure that material central to the page's meaning precedes material that is not.
• Divide pages into usable but limited-size portions.
• Create a logical order through links, form controls and objects.
• Create a means to navigate through to the start of content via a ‘Back’ button.
• Be consistent. For example, place buttons with specific functionality in the same place on the screen and design them consistently.
• Tabbed navigation lists in the footer of native apps should announce the number of tabs, the label of the tab, and the fact that it is selected. 

Full Explanation

Layout the page to enable users to experience all content by repeatedly scrolling in the same direction (axis). However, displaying content such as maps and other images may require secondary scrolling.

Suppose some element on the page requires secondary scrolling or swiping horizontally. In that case, it must provide an alternative way of performing this navigation (see article ‘Gestures’).

Also, it is essential that as the user navigates through, the various objects are presented in a logical order, especially as many of them may not be visible at the same time as the focus item.

Suppose you develop an application for an operating system or a mobile device that may have control buttons (for example, arrow keys and an OK button). It must be possible to use these to navigate the interface. These navigation guidelines currently apply to Android, for example, the physical 'Back' button must always work.