Apple OS X Lock Desktop / Screen

I need to prevent others using my desktop or laptop while I'm away from it. How do I lock my Laptop (Macbook or Macbook pro) / desktop using Mac OS X operating systems without using 3rd party applications?

You can lock your screen with password. First, you need to lock your computer screen:

1. Open System Preferences, and then click Security.
2. Select "Require password after sleep or screen saver begins."

Fig.01: Locking your computer screen

Keyboard Shortcut To Lock Your Desktop Screen

To put screen to sleep press [CTRL] + [Shift] + [Eject].

Menubar Shortcut To Lock Your Desktop Screen

Open Applications > Utilities > Keychain Access > Preferences >Select "Status in Menu Bar".

Fig.02: Apple OS X Keychain utility

To lock screen click on Menubar lock symbol > Select "Lock screen"

Fig.03: Locking the screen