Base Learner

General base learners can be composed of Logistic regression, decision tree, SVM, neural network, Bayesian classifier, K-nearest neighbor, etc.

If individual learners are generated from the same learning algorithm from the training data, it can be called a homogeneous ensemble, and the individual learners in this case are also called base learners; the ensemble can also contain different types of algorithms, which can be called a heterogeneous ensemble, and the individual learners are generally called "component learners."