Simply connecting your Windows Phone and opening the application allows you to transfer all of the content from your smartphone to your PC so that you can have all of your music, videos, documents, and applications on both systems.
This Windows Phone application for desktop lets you synchronize everything from your iTunes or Windows music libraries to your Windows Phone; it will automatically import all of your phone-captured photos and videos to your PC, you can easily view how much space each type of content is taking up to make sure you'll never run out of memory again, and also transfer playlists from your computer to your phone.
The application also gives you access to the Windows Phone Store so that you can download and buy whatever you want for your phone.
In all, it's a great application to synchronize content between your phone and your computer, and very practical for those of you who like to make backups of your multimedia content to your computer.
Some protected multimedia files (DRM) will not transfer between the PC and Windows Phone.