Gelatin is a tasteless, odorless substance extracted by boiling collagen, a jelly-like fibrous protein found in animal bones, tendons, hoofs and connective tissues.
When dried gelatin is mixed in warm water, the fine-grained particles do not actually dissolve, but rather become evenly dispersed and remain suspended in the liquid.
When cooled to 95 degrees Fahrenheit and below, the gelatin particles absorb five to ten times their weight in liquid, expanding into a coagulated semi-solid state or gel.
The cooler the environment, the more water is absorbed.