A factor that either restricts what is possible or what results, or determines a range of variations. In mathematics, a parameter may be a constant value in an equation that varies in other equations of the same general type, especially such a constant that describes a curve or surface, such that changing it changes the curve or surface in some way. It may also be a variable that stands for the coordinates of a point. And, in other sciences, a parameter may be one of a set of measurable factors ? such as temperature, volume, color, or acidity ? that define a system and determine its behavior.<br><br>A factor that either restricts what is possible or what results, or determines a range of variations. In mathematics, a parameter may be a constant value in an equation that varies in other equations of the same general type, especially such a constant that describes a curve or surface, such that changing it changes the curve or surface in some way. It may also be a variable that stands for the coordinates of a point. And, in other sciences, a parameter may be one of a set of measurable factors (such as temperature, volume, color, or acidity) that define a system and determine its behavior.