Root Node

• Definition: The topmost node of the tree.

• Function: It represents the entire dataset and is the first point where the data is split based on the most significant feature.

• Example: If you're predicting customer churn, the root node might split on "Contract Type" — the feature that best separates churn vs. non-churn.

Internal Node

• Definition: Any node that is not the root or a leaf.

• Function: It continues splitting the data based on other features, refining the decision path.

• Example: After splitting on "Contract Type", an internal node might split on "Monthly Charges" or "Tenure".