Cloud Computing (a simple view)
In the early days when PC's were difficult to use, Microsoft created Microsoft Windows and made computing easier, those who remember the 80's and using Word Perfect for DOS or any other DOS based program - will understand this all too well.
Though this is a simplistic view on what cloud computing is and how it has evolved, it is quite a logical evolution of a system we once knew and hated because of how difficult it was to do, but are starting to love because of how it has grown in terms of ease of use coupled with the increasing speed of the internet.
Dropbox, Google and other innovative companies, have made the transfer of files between the PC and the internet, easy, and now more and more of us are using the cloud to hold our data, e.g. your videos (via YouTube), your photos (via Facebook and Picasa) and your documents, presentations and spreadsheets (via Dropbox).