This unique book and accompanying CARAT software provides concise, exhaustive, and clear descriptions of terms, notations, concepts, methods, laws, and techniques that are necessary for engineers and researchers dealing with physical and chemical processes in gas and plasma dynamics. This first volume of a multi-volume set covers the dynamics of elementary processes (cross sections and rate coefficients of chemical reactions, ionization and recombination processes, and inter- and intramolecular energy transfer). The text and Windows-based computer program CARAT - toolkit from Chemical Workbench model library - carry widely diversified numerical information about 87 models for collision processes in gases and plasmas with participation of atoms, molecules, ions, and electrons. The processes include elastic scattering, electronic-vibration-rotation energy transfer between colliding molecules, and chemical and plasma-chemical reactions. The databases of recommended particle properties and quantitative characteristics of collision processes are built in. Computer implementation of models allows one to calculate cross sections for elastic and inelastic collisions, and rate constants for energy transfer processes and reactions within a wide range of parameters and variables, i.e., the collision energy, gas temperature, etc. Estimates of the accuracy of cross sections and rate coefficients represent an important part of the description of each model.