Instead of cutting and pasting data, Drag and Drop allows users to actually drag the text by using the mouse. Specifically, it does what cut and paste (or copy and paste, to some extent) does, but in a far more comprehendable manner and without having to resort to the Clipboard.
But Drag and Drop is not limited to the boundaries of the specific application programme. A blob of text or some graphics can be dragged even out on to the Desktop, where it ends up as a clipping. This clipping can be considered boilerplate text, and can be dragged back into a programme which supports Drag and Drop. Drag and Drop even works between different programmes, as long as they're all Drag and Drop-savvy.
Although applications have to be reprogrammed to take advantage of Drag and Drop, the new technology was quickly embraced.
In Mac OS X, Drag and Drop has not only been integrated into the system, but has been accepted by a great majority of applications, regardless of vendor.