An Introduction to Statistical Learning with Applications in R, Gareth James, Daniela Witten, Trevor Hastie, Rob Tibshirani, 2013 (Springer) - Introduces statistical learning concepts, including detailed explanations of data, features, and response variables.
Machine Learning, Tom Mitchell, 1997 (McGraw-Hill) - A classic textbook defining core machine learning principles, including how algorithms learn from data, features, and target concepts.