<p>This textbook is designed for advanced undergraduate and early graduate students. It provides a comprehensive overview of key concepts in thermodynamics, statistical physics, solid state physics, condensed matter physics, phase transitions, and critical phenomena. Ideal for use in multiple courses within the field of condensed matter physics, this book offers a thorough review of the essential material typically covered in these courses.</p><p>Unlike many textbooks that focus heavily on many-body techniques and complex diagrammatic methods, this book presents its content in a more accessible manner. It covers a broad range of topics, including some not usually addressed in introductory courses, while maintaining a technical level that is less intricate than traditional many-body texts. This book integrates graduate-level discussions with undergraduate material and simplifies advanced topics wherever possible. For students interested in exploring more challenging subjects, the book references additional textbooks and resources, enabling them to deepen their understanding of advanced concepts and methods.</p><p>This volume, the first of two, presents readers with a microscopic description of condensed systems and is mainly concerned with single-particle properties.</p>