Theoretical computer science (TCS) refers to a subset of computer science that deals with algorithmic and computational interactions and processes. It emphasizes on theoretical foundations of computer science and commonly depends on rigorous mathematical proofs. The goal of TCS is to understand the nature of computation and use this understanding to develop more effective methodologies. The primary uses of TCS are quantum computation and algorithm design. It encompasses a wide range of topics such as program semantics and verification, computational economics, computational number theory and algebra, machine learning, cryptography, algorithmic game theory, computational geometry, and computational biology. TCS has also played a vital role in the formation of various fields including algorithmic privacy, quantum computation, algorithmic fairness and algorithmic economics. This book contains some path-breaking studies in the field of theoretical computer science. It presents researches and studies performed by experts across the globe. This book is a complete source of knowledge on the present status of this important field.