Microsoft Office Web Apps allow you to store your files on the internet and access them from anywhere. You can use Office Web Apps to collaborate on documents online. More than one person can edit a file at the same time. You can use the Office Web Apps with just about any version of Office, or directly from your browser. Best of all, you get 25 GB of space for free!
Start by watching this video that shows what you can do with it:
First, you sign up for a Windows Live ID. If you already have a Hotmail or Live account that you want to use, you can skip this step and just log in with that ID. Once you have a Live account, you have access to your online storage area called SkyDrive.
To explore more features of Microsoft Office Web Apps check out these links.