The base element in lsFusion is the object. Each object is an instance of some class, which determines the qualities of all its instances. Classes in turn can be divided into built-in classes, which are responsible for primitive data types, and user classes.
Classes can inherit from each other. When class B inherits from class A, class A shall be called the parent, and class B shall be called the child.
Accordingly, if the class mechanism is not sufficient, the platform also supports the aggregation mechanism, which together with inheritance allows implementing almost any polymorphic logic.