What are Magento 2 design patterns?

magento 2 design pattern.

Design patterns are the common dictionary that computer science engineers use to describe a software architecture.
For example, see the code:
https://github.com/magento/magento2/blob/cf7df72/app/code/Magento/Config/Model/Config/Structure/Element/Iterator.php#L41-L44
When I see such code I need not spend any time to understand what is the _flyweight field for because it is a standard design pattern term:

Magento 2 uses a lot of design parterns. The most frequently mentioned is observer.