A fluid refers to a state of matter that yields to shearing or lateral forces. Fluid mechanics is a branch of continuum mechanics which is involved in the study of fluid behavior in motion and at rest. It is categorized into fluid dynamics, which studies the effect of forces on fluid motion; and fluid statics, which studies fluids at rest. The energy equation, continuity equation and momentum principle are the basic fluid mechanics principles. Some of the important areas of study within this field are biofilms, dynamics of bubbles and droplets, aerodynamic shape optimization, fire whirls, drag reduction and fish locomotion. The topic of fluid mechanics is studied under various disciplines such as chemical engineering, mechanical engineering, civil engineering and aerospace engineering. This book aims to shed light on the key topics in fluid mechanics. It consists of contributions made by international experts. Scientists and students actively engaged in the study of fluid mechanics will find this book full of crucial and unexplored concepts.