Like an external hard drive, iDisk is a convenient online storage service attached to your Mobile Me account. It can be accessed from a Mac or PC directly, or via the me.com web portal.

Essentially, iDisk exists to store important files that you need access to everywhere you go. But a more useful application of iDisk is to use it for sharing large files. Rather than sending large attachments over email (which often gets rejected), you simply upload a file to iDisk and share the link with the person you want to send the file to. They can download it themselves and you have it for future access on other devices.

In a way, iDisk is similar to other web-based services like YouSendIt or DropSend, apart from the fact that iDisk keeps your files in your dedicated online storage space. It also has greater protection, allowing you to enable a password on the files you want to share and limit the number of times it can be downloaded as well.