Publisher Summary This chapter presents an overview of laminar flow. If the fully established flow in a duct is laminar; then the velocity distribution over a cross-section can be obtained quite easily, because at any given time only pressure and viscous forces act on a fluid particle. In particular, for both axisymmetric symmetric flow (as in a duct with circular cross-section) and plane flow (as in a gap between two plane walls) the velocity distribution can be represented as a parabola. The mean velocity of the flow V/S is denoted by c¯; for flow through a duct with a circular crosssection of diameter d, the velocity at a distance r from the axis is c. The chapter gives an expression for the velocity at a distance y from the center for flow through a gap of width a. It is highlighted that the shear force on the walls of a section of the duct must be in equilibrium with the difference between the pressures on the two cross-sections forming the ends of the section.