Waft is a term meaning to "carry along gently as through the air." The term is commonly used to describe scents that have diffused into other parts of a room, or to describe smoke as being seen moving through the air. Wafting may be used for everyday substances, to make sure they are fresh, or consumable.
In chemistry and other sciences, it is a term of laboratory safety. In "wafting" a person takes an open hand with the palm towards the body and moves their hand over the substance in a gentle circular motion so as to lift vapors of the substance towards the nose. This method allows for a lower concentration of vapors to be inhaled and is particularly useful in safely smelling ammonia, hydrochloric acid, and other dangerous or unpleasant chemicals.