The Elements of Statistical Learning [pdf]
To echo some of the other comments here, this is a text that's really only appropriate for those who already have a graduate-level grasp of statistics. I love that it's freely available, but ESL is not an introductory text.For example, here's a screenshot from the introductory chapter (pg. 26): [1]. The authors expect you to already be familiar with matrix analysis applied to statistics.An Introduction to Statistical Learning (ISL) [2] is aimed at those with a high school level of math.[1] https://imgur.com/q0NeqdR
[2] https://statlearning.com/book.html