Fast Startup is a new feature which is introduced in Windows 8 RTM. It allows your computer to start faster than normal by logging off the user session and then saving a part of system related files and drivers to a hibernation file. When you turn on your PC again, it resumes from hibernate and logs you in again. In other words, the fast startup feature combines the classic shutdown mechanisms with hibernation, so it can be called 'hybrid shutdown'. Hybrid shutdown is enabled by default in Windows 8 and its successor, Windows 8.1. Follow this article to learn how to disable the fast boot feature or enable it back, and why you may want to do so.