Multilevel Categories & Menu - How To? I would like to be able to create content of a particular type but be able to set multi-level categorisation. But I would like a menu where I can select a category and see all content including child categories as well.

e.g.


Fruit


Local


Apples
Pears

Tropical


Pineapple
Bananas




'Fruit' menu would show all fruit

'Local' Menu would show all local, apples and pears

'Apple' Menu would only show Apples

I am trying to achieve some thing like this side menu:
http://learningexchange.ptc.com/tutorials/by_product/ptc-creo/product_id:1
There won't be a definite answer to this question as this can be achieved in a lot of possible ways. Depending on your knowledge in drupal you could start with the built-in drupal taxonomy system that enables you to classify your content as needed (e.g. with a tree-like-hierarchy or even related terms). To build the menu you can try the taxonomy menu module or use Views to create this manually. 

For a start i recommend reading through this overview: https://www.drupal.org/documentation/modules/taxonomy