This text provides an introduction to the structure and function of biomolecules - especially proteins - and the tools used to investigate them. Biomolecules obey the same laws of physics as their constituent atoms, but their complexity introduces properties and behavior not found in simpler systems, including beautiful and subtle properties exploited by living systems. The text focuses on physical tools and properties, highlighting techniques that contribute to new developments. New tools appear regularly: synchrotron radiation, proton radiology, holography, optical tweezers, and muon radiography, and the book shows how these contribute to a richer understanding of biomolecules.