What is the difference between CART, ID3, and C4.5 algorithms?
Updated May 16, 2026
Short answer
CART uses binary splits and Gini, ID3 uses entropy, and C4.5 improves ID3 with gain ratio and pruning.
Deep explanation
ID3 builds trees using information gain and handles only categorical features. C4.5 extends ID3 by handling continuous features, missing values, and uses gain ratio to reduce bias toward high-cardinality features. CART (used in sklearn) always produces binary trees and supports both classification and regression using Gini impurity or MSE. CART is widely used in production due to efficiency and simplicity.
Real-world example
CART is commonly used in fraud detection systems; C4.5 is often used in academic datasets.
Common mistakes
- Assuming all decision trees use entropy-based splitting.
Follow-up questions
- Why is gain ratio used in C4.5?
- Which algorithm is most widely used today?
- Does CART support regression?