How to: enable the Start screen in Windows 10
If you are coming from earlier releases such as Windows 8.0, be prepared for some changes. Functions such as Semantic Zoom, Start Tip are either no longer available or have been relocated and renamed to new functions.
To enable the Start Screen (now called Tablet Mode) just open the Notification Center in the Notification Area of the Taskbar and click Tablet mode.
then you will be in Start mode like Windows 8. Instead of scrolling horizontally, you will scroll vertically and you can click the hamburger menu to access your application library:
One of the immediate differences you will notice, the Taskbar is always on screen.
Applications are not hosted on the Taskbar in Tablet mode, instead, you will find your running programs by clicking on the Taskview icon next to Search.
You can also cycle through apps using Alt + Tab if you are using a keyboard
Launching Apps and programs
To launch an app, click or touch the Start button to bring up the Start.
Launch a favorite app if it is already pinned to the Start. If its not there, click the Hamburger menu at the top left corner of the screen and launch from the most used list or the All Apps list.
Notice you can also access functions such as Jump List which was not previously available.
Accessing my entire application library.
When you want to exit Tablet Mode, click the Notification icon and click Tablet mode to exit.
Enable full screen Start screen without the Tablet features.
If you prefer to not have the Tablet features, you can still enable a full screen from within Settings.
Click Start > Settings or Windows key + i
Click Personalization then click Start
Under Start behaviors, toggle the on switch Use full-screen Start when in the desktop
You now have the best of both worlds.