Hard-and-fast, black-and-white rules for getting started with Object-Oriented Programming

No object should have more than three public methods

Objects should not have getters or setters

Everything else must be private

If three private methods are doing something similar, then maybe those are the public methods of another class

Never inherit

Always compose

Changeability is the most important thing

A "good" variable name is a name that describes unambiguously what the variable contains, without describing the implementation

If you don’t use good variable names, I will look for you. I will find you. And I will kill you.¹