Designer needs to cue the user that an interactive feature exists.
Designer needs to cue the user that an object can be interacted with.
Designer needs to indicate valid candidate drop sites during a drag and drop operation.
Designer needs to cue the user about what will happen when the mouse is clicked on the hovered object.
Designer needs to cue the user about what will happen if they click the mouse on the hovered object.
With the more widespread adoption of Ajax and the resurgence of Flash on the web page, more subtle interactions are possible. Instead of a read-only web, we can now have a read-write web. Where before all content on the page was view-only, the user can now edit selected content directly. This inline editing capability is not immediately discoverable. The idea behind an invitation is using as many avenues as possible to get the user to discover the feature through lightweight interaction (e.g., mouse hover).
Invitations are good when:
Since invitations are about visual communication they by default are not accessible by users with visual impairments. To make the invitation accessible try the following techniques.