Saline solution is a solution of sodium chloride, or salt, in sterile water. Normal saline solution is 0.9% sodium chloride, though this refers to only one possible concentration.
Saline solution for rinsing and storing contact lenses may sometimes contain other chemicals for sterilization, and it is not recommended that contact lens solution be used for nasal irrigation without being certain it is a normal saline solution.
As an intravenous infusion, a saline solution is typically mixed with dextrose or glucose to reduce any complications from infusing saline solution and to reduce the amount of sodium circulating through the blood stream. This works particularly well as a water and nutrient supplement to sustain hospitalized patients who are unable to eat or drink or who have suffered dehydration from severe vomiting or diarrhea.
Excerpt from http://www.wisegeek.com/what-is-saline-solution.htm
