Dropbox users save more than a billion files a day

"To hear the founders tell it, the plan is refreshingly simple and easy to understand for a Silicon Valley striver. The more places Dropbox touches people, the more people will put stuff in their Dropboxes. And the more stuff you put in Dropbox, the more you come to rely on your pervasive data — the more likely you are to pay for more space. Dropbox doesn’t say how many of its 175 million users are paying customers, though the company does say those users add 1 billion files to the service every day. Some of those people will need more space."

Source:  Wired, 9th July 2013

Note - Dropbox themselves describe this as 'syncing files'