Fluids plays vital role in many aspects of everyday life. We drink them, breathe them, swim in them. They circulate through our bodies and control our weather. Airplanes fly through them; ships float in them. A fluid is any substance that can flow; we use the term for both liquids and gases. We usually think of a gas as easily compressed and a liquid as nearly in compressible, although there are exceptional cases. We begin our study with fluid statics, the study of fluids at rest in equilibrium situations. Like other equilibrium situations, it is based first and third laws. We will explore the key concepts of, pressure, buoyancy, and surface tension. Fluid dynamics, the study of fluids in motion, is much more complex indeed, it is one of the most lex branches of mechanics. Fortunately, we can analyze many situations using simple idealized models and familiar has laws and conservation of energy. Even so, we will scratch the surface of this broad and interesting topic.