Letting your employees access the corporate network remotely has been traditionally done with VPN. There have been many technologies and solutions along the way, but DA is by far the most user-friendly (to your users, not to you, that is). While all other solutions require the user to launch some kind of application or link, DA is "always on"—as soon as the user's computer departs his corporate network and connects to the public internet anywhere in the world, DA initiates the connection silently, without bothering the user with configurations or even a single mouse-click. From then on he is, for all intents and purposes, "still" connected to his corporate network. This is completely transparent, and unless there's some malfunction or specific blockage on the network the user is a guest on, he could have completely unrestricted access to all his corporate resources, just as if he was in the office.
That's not all, of course—the administrative overhead is also reduced...