Dropbox

Dropbox is the easiest way to store, sync and share files online. Dropbox works just like any other folder on your computer, but with a few differences. Any files or folders inside Dropbox will get synchronized to Dropbox's servers and any other computer linked to your account. Green checkmarks will appear on top of your files to let you know that they're synced and up to date. All data is transferred over SSL and encrypted with AES-256 before storage. Dropbox keeps track of every change made to any of its contents. It's free to download and use 2GB of online storage for free, with up to 1TB available to paying customers.