Classes
There is a common type of computer languages known as "Classical Object Oriented Languages". Programs written in these languages are expressed in terms of objects belonging to classes. Classes are arranged in hierarchies.
When you work with these languages to model real life problems, you write programs expressing your models in terms of class hierarchies.
The amazing thing is that once you get accustomed to use these languages, it becomes very hard to model problems without using class hierarchies.
The way you think about reality is determined by the language used to express your thoughts.
