Herein, we will discuss statistics in great depth, since the fundamental concepts of Statistics (and Probability, which is covered separately) forms the backbone for the Skeleton of Data Science and Machine Learning, and some parts of Deep Learning too!
Do checkout the sub pages of this page to get more in depth knowledge on variety of areas of Statistics. Meanwhile, the recommended books on this subject, which should always be part of the lifelong study/learning in this domain/field are provided below.