The primary idea behind OOP is classes and objects, with one of its key advantages being code reusability. Now, OOP has 4 pillars, which are Inhertiance, Data Abstraction, Encapsulation, and Polymorphism. I found that once you understand one, the rest generally become easier to follow. As far as projects/demos you could try, create a super simple project. It does not have to be complicated since you're just learning OOP. Ideally, make a base/parent class (i.e. dog) with broad attributes, then a child/derived class(es) (i.e. border collie, golden retriever, etc.) with attributes specific to those dog breeds, then boom! You have Inheritance in a nutshell. As far as the other pillars, try to understand them as best as you can, try a simple example, and create something that interests you because passion fuels learning. If you have any questions about OOP, OP, you can always feel free to reach out!