Let's see a few common problems of file management for commoners:

• They never care about backing up their data as it is usually too cumbersome.
• They work on multiple PCs and their head aches about synchronising all of their stuff between computers. Or they are working on a project and they keep passing around files by flash disk or e-mails and forget which person has which version and which files are the latest version.
• They keep the history of their documents neatly by appending phrases: "Letter to X.doc", "Letter to X (boss amend).doc", "Letter to X (final).doc", "Letter to X (final amended).doc", "Letter to X (final final).doc", "Letter to X (real final).doc" (which become less and less intuitive on each iteration!).

I was one of all those people once --- but not anymore because of a free service called Dropbox. It makes backup, sharing, and versioning a snap for everyone. Zero learning curve.

Dropbox designates a folder in your computer as your -- well -- "drop box"; any files in there will be uploaded to Dropbox server and will be synchronised with every "drop box" folder in every computer having Dropbox installation. If you edit the files, only your edits (the "diff") will be transmitted to the server, and it will keep the former version of your file for you to retrieve later from the web interface. Therefore all the contents of the folder will be properly backed up on the Dropbox server and versioned.

What's more, you can also share a folder in your dropbox to other dropbox users -- effectively making one of your folders available for your friend's edits. So a folder can be shared among project members and all of them will always have the latest version of the files within the folder. Coupled with the basic versioning feature, this makes it the ultimate sharing solution. (More-technical people will use more sophisticated versioning system, obviously.)

A particularly interesting application of this sharing technique is managing files on a web server using Dropbox. Basically all edits on your computer will be reflected on the remote server without any effort (and versioned too)! And all files uploaded by users on your website will be downloaded automatically to your computer! Currently, however, the client must have a background process for it to function, so this technique cannot be used in shared web hosting environment. What I would be very looking forward to is a version of dropbox PHP client without ongoing process, so that I can use it to manage files in a shared web host.

Dropbox can also create an online photo gallery for you --- photos you uploaded to the "Photos" folder will appear on the gallery. Also, if you are in need of sharing files to a few people that doesn't have dropbox account, you can put them in the "Public" folder and let people download the file straight from your dropbox; no need to resort to Mediafire and the likes!

Now all of these problem sets have their own solution sets in the web. But what makes Dropbox interesting for me is its ease of use: you don't need to learn some cryptic command line instructions, boringly upload files one by one, or learn a whole new world of version control system to take advantage of it. You just need to move files to a folder! What can be easier? (Note: sharing multiple folders and ignoring some files will be a feature someday, and even today you can still use junctions or symlinks to simulate the feature. Search in Dropbox wiki for more information.)

Free accounts are 2 GB in size which should be enough for private files. Even if you don't share files often, backing up your data will do you good once your hard disk fails or your laptop is stolen (I hope they don't happen). Make sure that you provide a strong password to protect your privacy!