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lessons/Encapsulation.md

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+# Encapsulation
+
+Encapsulation is a simple lesson, this one is not gonna need any code examples.
+
+There are typically 3 keywords you need for encapsulation: private, protected
+and public.
+
+## Private
+
+Private methods and fields are only acessible from within the same class, they
+can't be read or written from outside.
+
+## Protected
+
+Protected is just like private, but descendant classes can access them.
+
+## Public
+
+Public is accessible from anywhere.
+
+## The static modifier
+
+Static is another one of those keywords, although it doesn't really control
+access to fields and methods. Anything with the static keyword can be used
+without an instance of the class. That means you can directly access with with
+Class.property instead of creating an instance of that class first. This is used
+for example in java for the main method, since it needs to be accessible without
+running any of the programs code first.
+
+Encapsulation is not a safety feature, it's only to make clear, which properties
+should be used by others. Methods like reflection and directly reading/writing
+memory can still access private or protected properties.

lessons/Inheritance.md

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+# Inheritance
+
+Inheritance is useful to minimize code duplicates and generalize types in base
+classes.
+
+A Class can inherit all public and protected functions and fields from a base
+class and add its own or override existing ones. Private fields and functions
+still exist in the base class, but can't be acessed from the extending class.
+
+## Examples
+
+- [Java](../java/inheritance/README.md)
+- [Rust](../rust/Inheritance.md)
+- [C++](../cpp/inheritance/README.md)
+- [JavaScript (using TypeScript)](../typescript/inheritance/README.md)