Streamlining reduces the amount of resistance experienced by an airfoil.
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Streamlining is the shaping of an object, such as an aircraft body or wing, to reduce the amount of drag or resistance to motion through a stream of air. A curved shape allows air to flow smoothly around it. A flat shape fights air flow and causes more drag or resistance. Streamlining reduces the amount of resistance and increases lift.

To produce less resistance, the front of the object should be well rounded and the body should gradually curve back from the midsection to a tapered rear section.