Aromaticity of multi annuli systems

In high school books, Huckel's rule is used for determining aromaticity. We were taught this example 


[![enter image description here](https://i.stack.imgur.com/asnoR.png)](https://i.stack.imgur.com/asnoR.png)


Huckel's rule is limited to monocyclic systems. We were taught to find aromaticity by - 


1. looking for a closed loop. The two loops that were pointed out have been drawn (in pink) in the diagram above.
2. Applying Huckel's rule to it i.e counting the number of $\pi$ electrons and then applying the 4n+2 formula for aromatic compounds and 4n for anti.


No explanation was provided as to why this concept works on the grounds of 'this is out of syllabus'. 




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I have multiple questions regarding this 'closed loop' concept 


1. What is it really called?
2. How does this loop methodology work?
3. What would happen if the inner loop was aromatic and outer anti aromatic?  

(the example has both loops anti)


