This book is an introduction to the mechanical properties, the force generating capacity, and the sensitivity to mechanical cues, of the biological system. To understand how these qualities govern many essential biological processes, we also discuss how to measure them. However, before delving into the details and the techniques, we first learn the operational definitions in mechanics, such as force, stress, elasticity, viscosity and so on. Mechanics is explored at three different length scales – molecular, cellular, and tissue levels – sequentially, and measurement techniques to quantify the intrinsic mechanical properties are discussed, along with force generating capacity, mechanoresponsive processes in the biological systems, and rupture forces.