Machine learning is programming computers to optimize a performance criterion using example data or past experience. We have a model defined up to some parameters, and learning is the execution of a computer program to optimize the parameters of the model using the training data or past experience. The model may be predictive to make predictions in the future, or descriptive to gain knowledge from data, or both. Arthur Samuel, an early American leader in the field of computer gaming and artificial intelligence, coined the term ¿Machine Learning¿ in 1959 while at IBM. He defined machine learning as ¿the field of study that gives computers the ability to learn without being explicitly programmed.¿ However, there is no universally accepted definition for machine learning. Different authors define the term differently.