I already wrote about this in my OLD POST for finding Macbook Pro hidden keys / characters which are not directly visible on Macbook. These characters are frequently used by programmers or writing some technical things.
I received a wonderful advice which made things very very simpler. I am going to just elaborate his comments.
Here are the following steps for finding the keys:
1. Goto “System Preferences“
2. Select “Keyboard“
3. Check the box that says “Show Character & Keyboard Viewer in menu bar“.
4. Once this is selected you can click on the icon in the menu bar next to your battery status.
5. select “Show Keyboard Viewer“.
This will give you an onscreen keyboard that shows what symbols are available when you push special keys like the “alt“, “command” and “control” keys.