The user needs a way to perform operations on one or more objects by being able to move objects from one place to another directly with the mouse.
The user needs needs to re-arrange the layout of modules on a web page directly with the mouse.
Designer needs to indicate valid candidate drop sites during a drag and drop operation.
Drag and Drop is a shortcut mechanism that allows users to perform more complex tasks through direct manipulation. It follows good design principles such as What-you-see-is-what-you-get (WYSIWYG), keeping information in context and using direct manipulation.
The following interesting moments can be important during a drag and drop interaction. A good solution will consider each of these moments below (a specific drag and drop pattern may choose to ignore some of them.)
In addition, the following interface elements play a role in some or all of the states above: