Online desktop (some call it online operating system, or WebOS) literally means putting the whole operating system online and allow users to have their own desktop where they can access anywhere in the World with an Internet connection.

Just like your desktop in your PC, there will be a standard suite of software such as the email client, office suite, IM, contact available in your online desktop. The idea behind it is to promote mobility and enable users to share and access their files easily. If you are always on the move and hate the feeling of lugging your laptop around, then syncing your local desktop with an online desktop might be a good idea for you.