The chapter briefly describes the overall domain of computer science. It is well known that computer science is one of the main reasons behind the development and transformation of the twenty-first century. This book begins to introduce the readers to the mathematical and logical foundations of computer science. It is followed by an elaboration on the rise of computer science algorithms; computation techniques; Internet penetration to the masses; evolution of different types of computers; and the modern prevalent computer science techniques, paradigms, and technologies. It finally explains how computer science has evolved into a set of diverse technology domains encompassing artificial intelligence, machine learning, quantum computing, big data, cybersecurity, blockchain, and human–computer interaction. It then emphasises how the interdisciplinary nature of computer science influences and helps different roles in industries such as healthcare, governance, finance, and education. The ethical considerations surrounding data privacy, algorithmic fairness, and automation are also discussed. The chapter finally summarises the importance of computer science in framing and modernising the digital era and prepares readers with the conceptual foundation to engage with its future frontiers.