This book is a clear, readable and self-contained introduction to particle physics and related areas of cosmology. It represents a resource that bridges the gap between non-technical popular accounts and in-depth textbooks for more advanced students. It is therefore suitable for an introductory course at undergraduate level. The book concentrates on presenting the subject from the modern perspective of quarks, leptons and the forces between them. This approach enables readers to grasp the essential concepts more easily than the traditional historical approach involving the complex interactions of hadrons. Necessary background material on relativity and quantum mechanics is included but advanced mathematics is avoided. The book assumes a knowledge of physics to roughly senior secondary school level.