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".