XGBoost is an open-source software library which has won several Machine Learning competitions in Kaggle. It is based on the principles of gradient boosting, which is based on the ideas of the Leo Breiman, the creator of Random Forest. The theory behind gradient boosting was later formalized by Jerome H. Friedman. Gradient boosting combines weak learners just as Random Forest. XGBoost is an engineering implementation which includes a clever penalization of trees and a proportional shrinking of leaf nodes.