Suction's the flow of a fluid into a partial vacuum, or region of low pressure. The pressure gradient between this region and the ambient pressure will propel matter toward the low pressure area. Suction's popularly thought of as an attractive effect, which's incorrect since vacuums don't innately attract matter. Dust being "sucked" into a vacuum cleaner's actually being pushed in by the higher pressure air on the outside of the cleaner. The higher pressure of the surrounding fluid can push ma… (More on Suction)