Advanced R by Hadley Wickham is an in-depth exploration of the R programming language, designed for users who want to move beyond basic data analysis and gain a profound understanding of R's internal mechanisms. The book systematically covers foundational concepts like object-name binding, data structures, and the behavior of functions and environments. It then dives into key programming paradigms: functional programming, which emphasizes composition and immutability, and object-oriented programming, with a detailed look at S3, S4, and R6 systems. A significant portion of the book is dedicated to metaprogramming, explaining how to manipulate R code itself, a crucial skill for developing sophisticated R packages and domain-specific languages (like the tidyverse). Finally, it provides practical guidance on debugging, profiling, and optimizing R code, including how to leverage C++ for performance enhancement. The book aims to equip readers with the knowledge to write more efficient, maintainable, and robust R programs by understanding why R behaves the way it does.