Dropbox is simple in concept. The initially free service offers online storage in much the same way that e-mail portals like Gmail and Yahoo Mail do, only users can upload any files they want, provided they have the space. A basic account gives you 2GB of remote storage to fill up, though that number can be increased either with a paid account or by referring new users.

It is an enormously useful service for those who have data they’d like to keep safe, which in this day and age amounts to roughly everyone. People are starting to catch on too, as the company has seen enormous growth in the past year. There are now 25 million users signed on with Dropbox, TechCrunch has learned. It is an exponential increase over last year’s number of 4 million and 2009′s 2 million. Those 25 million users are remotely storing 200 million files daily, which amounts to roughly 1 million uploads every five minutes.

While Dropbox is not without its competitors, the cloud storage service scores high marks from users for offering the option of syncing all content across multiple platforms. There are mobile apps and desktop clients for just about every operating system out there, offering instant access to remotely stored content for those who use multiple web-connected platforms in the course of their daily business dealings.

TechCrunch has the word from Dropbox in advance of its official news release, which should be coming sometime today. Interestingly, there is no mention of how the rising number of users has impacted the company’s earnings. That free 2GB of storage is plenty for an average user who is mainly concerned with backing up important text documents.

Larger businesses take advantage of the service’s sharing features to distribute materials to groups, but it’s a safe bet that the larger portion of those 25 million users are signed up for just the basic free package. The question now is if the dramatic rise in usage will lead to any changes in the company’s business model, since more people means more bandwidth and more total storage space being consumed.