Abstract: As kids, we all have learnt that by planting a seed in the ground and watering it regularly we can grow a tree. Of course there are other ways to grow trees. Here we won't talk about trees that give us oxygen. Instead, we will present special kinds of trees known as "Decision Trees" that are generated from data and can be used as predictive models for classification and regression problems. Firstly, we will define decision tree learning. Then we will see the Classification And Regression Tree (CART) algorithm for growing (splitting strategies) decision trees due to Brieman et. al.