Let’s talk about syncing files. I’ve got a new program you ought to know about.

Imagine that you have a folder full of files and you want to have a copy of that folder on another computer. There’s a lot of reasons to do that: to take your work files or photos with you on a laptop; to have a backup of a folder with important files; or to share files with a friend.

In other words, you want to sync the copy with the original – have the copy mirror the original, periodically or all the time.

There are many ways to accomplish that. Here’s two ways for files located on computers that are physically connected to each other or connected to the same network, for example.

  • On a network with shared files, Windows XP Professional can do that using Offline Files. Instead of working directly on the files in a shared folder on the server, your workstation invisibly makes a copy of those files. The copy is always identical with the server files while the computer is connected to the server. If the workstation becomes disconnected from the network, you can continue working on the copies of the files; when you reconnect, new or changed files are copied each direction. Many people never realize the syncing is going on – there’s no sign except a flash of a “synchronizing” dialog when the computer starts or shuts down.
  • Microsoft developed a free program named SyncToy that can create copies of folders between two devices in a number of ways. I use it to copy all the folders with family photos to an external hard drive. SyncToy runs on one computer and copies files anywhere – to another computer on a network, to an external hard drive, to a USB drive.

Now FolderShare offers a way to sync folders full of files across the Internet. The service was originally developed by a small company but it was purchased by Microsoft last year. Microsoft removed any charges for the service – it’s completely free now – and says it will continue to have it available for both PCs and Macs. It is fascinating, powerful technology.

After you install a small bit of software, Foldershare does three things:

  • It allows you to set up folders on your own computers that are kept in sync with each other across the Internet, whenever both computers are online. For example, you can make your entire office document folders appear in a folder on your laptop; if you create or edit documents on your laptop, those changes immediately show up in the synced folder on the office computer.
  • It allows you to set up folders that are shared with your friends. Anything you put in those folders shows up in a folder on your friends’ computers – automatically, quickly. There are pretty trivial restrictions (effectively there’s no restrictions on file size, and not much of a restriction on the number of files – you can’t share folders with more than 10,000 files).
  • It allows you to log into your computer from anywhere, using a web browser, and download any file from your computer.

Now read that list again! Think about it. When this software is running on your computer, you can retrieve any file from it, any time, from anywhere. You can share files that are too big for e-mail. You can send a hundred photos to mom, and update them the following week.

(There is a restriction that will affect some people – files cannot be shared from a network drive; the software must be running on the computer holding the files to be shared.)

Many people report that the service works flawlessly. It has in my experience. The problem is that it is conceptually hard to grasp. There are only a few vocabulary words to learn (a synced folder is called a “library,” for example) and the interface is very streamlined on the web site and the software, but I still found it difficult to get started with it and explain it. When you set up a library with FolderShare and you sync it between two computers or you share it with a friend, it looks just like any other folder on your computer. It takes a while to understand that there are two folders, two complete sets of the files, one on each computer – but changes at one end are immediately reflected on the other end.

It’s weird. It’s confusing at first. But this may have the power to open up important new ways to work from outside the office, to share photos or music or videos, or more.

Think about it. Check it out. Here’s a review and here’s a blog entry to get you started. This is big stuff.