The article examines five different types of models that explain how economies grow on their own. They start with a basic model and show how all the others are connected to it. One model talks about how government spending can boost growth. Another model looks at how learning new things and external factors help an economy grow. Also, there's a model that focuses on how people learning new skills can make an economy stronger. Lastly, a model shows how research and development activities can make an economy grow faster. All these models help us understand why and how countries become more prosperous over time.