This textbook provides an accessible introduction to the basic concepts of relativistic cosmology and the standard big bang model of cosmology, along with an introduction to quantum field theory and the standard model of particle physics. Readers are guided through the key concepts associated with the standard model of cosmology and the standard model of particle physics, providing them with the basic foundation needed to understand current research and literature on the physics of the early universe and modern particle physics. It culminates with an introduction to the physics of the early universe and its imprint on the large-scale structure and the cosmic microwave background.It assumes a basic understanding of quantum mechanics, classical mechanics and electromagnetism.It is aimed at advanced undergraduates and first year beginning graduate students studying particle physics and/or cosmology. Key Features:Provides a summary of the state-of-the-art tools and developments in cosmology and features end of chapter problems, alongside the basic tools for studies of inflation theory and early-universe cosmologyProvides an understandable introduction to special and general relativityIncludes an understandable introduction to the standard model of particle physics including group theory, gauge theories, quantum field theory, the Higgs mechanism and the Electroweak Lagrangian