Windows 8 is a personal computer operating system developed by Microsoft as part of the Windows NT family of operating systems. Development of Windows 8 started before the release of its predecessor, Windows 7, in 2009.

Features of Windows 8

•  The secret Start menu-: Moving your mouse cursor down to the bottom-left of the screen and left-clicking switches to the tiled Start page... but if you right-click instead, you'll be met with a menu linking to key areas of the operating system, including Control Panel, the command prompt and the Task Manager.
•  Sync your settings.
•  Windows Defender-: Windows Defender is back from extinction, taking over from Microsoft Security Essentials.
•  Simpler shutdown-: Rather than opening the Charms bar, clicking Settings, selecting the Power button and choosing 'Shut down', simply press Alt+F4 while viewing the desktop.
•  Built-in screenshots-: Windows 7 had the Snipping Tool for taking screenshots, and this tool is still around in Windows 8.
•  Reinstall Windows-: Here's a feature you might not come across until something goes wrong - Windows' new reinstall routine, known as Reset (on the PC Settings page).

There's no need to dig out discs or serial codes, because everything you need is already available, hidden away on the hard drive

If your system have any problem and you want to run OS as Safe Mode then

follow below steps to open OS as Safe Mode

1.   Press or Use Shift + Restart. When you restart your system then you have need to press Shift button and with Restart option. 

2.   Windows asks you to choose an option. Press Troubleshoot. 

3.  In the Troubleshoot screen, press Advancedoptions.

4.  In the Advance options screen , press Startup Settings. 

5.  Your computer or device restarts again and displays nine startup settings, including Safe Mode, Safe Mode with Networking and Safe Mode with Command Prompt 

Press the F4 key on your keyboard, to enable Safe Mode, F5 to enable Safe Mode with Networking and F6 to enable Safe Mode with Command Prompt. Windows 8 and Windows 8.1 now boot according to the setting you selected.