What is dependent and independent variables?

What is dependent and independent variables?

I would like to give an example over here. We know that smoking is injurious to health, and may cause cancer. So we can write it as;
“Smoking cause cancer”

In this statement it is clear that cancer is dependent upon smoking because due to smoking there is a possibility of having cancer. But in the other hand, habit of smoking is not related or dependent upon cancer because everyone can smoke and it is independent of cancer patient.
So from here we can say that
Smoking (Independent Variable)
Cancer (Dependent variable