A "101 books series" typically refers to a collection of introductory or beginner-level books on various topics. These books aim to provide basic knowledge and understanding to readers who are new to a particular subject or want to gain a foundational understanding.
Each book in a "101 series" usually covers a specific topic or subtopic, providing a broad overview, key principles, and essential information. The intention is to offer readers a solid foundation to build upon if they choose to explore the subject further.