Dropbox

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.