Modality is a design technique that presents content in a temporary mode that’s separate from the user's previous current context and requires an explicit action to exit. Presenting content modally can:
- Help people focus on a self-contained task or set of closely related options
- Ensure that people receive and, if necessary, act on critical information
Alerts, sheets and popups are modal content.
Use modality when it makes sense. Create a modal experience only when it’s critical to focus people’s attention on making a choice or performing a task that’s different from their current task. A modal experience takes people out of their current context and requires an action to dismiss, so it’s essential to use it only when it provides a clear benefit.
Reserve alerts for delivering essential — and ideally actionable — information. Typically, an alert appears because something has gone wrong. Because an alert interrupts the experience , it’s important for people to feel that the intrusion is warranted.
Keep modal tasks simple, short, and narrowly focused. Avoid creating an app within your site. If a modal task is too complex, people can lose sight of the task they suspended when they entered the modal context. Be especially wary of creating modal tasks that involve a hierarchy of views because people can get lost and forget how to retrace their steps. If a modal task must contain subviews, provide a single path through the hierarchy and a clear path to completion. Avoid using a Done button for anything other than completing the task.
Always include a way to dismiss the modal view. For example, you might use Done or Cancel. Including a button ensures that the modal view is accessible to assistive technologies and provides an alternative to dismissal gestures. Alternatively, make sure that the modal is dismissed when clicking outside.
In general, display a title that identifies the modal task. When people enter a modal task, they switch away from their previous context, so it’s a good idea to make the new context clear. You might also provide text in other parts of the view that more fully describes the task or provides guidance.
Coordinate the modal view appearance with your site. Make sure you use the same UI views and controls on your site and on the modal view.