This book begins by providing a simplified version of the computational quantum chemistry sufficient to calculate the wavefunctions that are the basic input of NG-QTAIM. Enough basic (scalar) QTAIM theory is provided to understand the later chapters. In addition, our developments of scalar QTAIM are presented and activities at various levels of difficulty are provided for the readership to facilitate understanding.The topological origins of Quantum Theory of Atoms in Molecules (QTAIM) before explaining the highlights and consequences of the developments of Next-Generation QTAIM (NG-QTAIM)...