At low velocities, fluids tend towards laminar, or streamlined flow, meaning that the material is traveling smoothly within its boundaries. The term laminar is used because the fluid can be described as having "layers" which slide across each other easily, forming a stable velocity profile in the fluid. Streamlined flow refers to the fact that the path traveled by any given infinitesimal volume of the fluid will show a trajectory, dubbed a streamline, on which particles are always moving in the same direction over the distance specified, as long as the flow remains laminar.
A fluid flowing through a set of boundary conditions, (for example, water through an infinite pipe) at low enough velocity to be laminar, forms a parabolic velocity profile. The fluid touching the walls of the pipe are dragged down by the friction between the fluid molecules and the pipe wall and will theoretically approach zero velocity, while the fluid at the center of the pipe is traveling at the highest velocity of all the fluid in the pipe, and forms the leading edge of the velocity profile.