The word parameter is used in different ways, usually as a name for symbols that remain constant in a given situation.
A textbook will most likely refer to these as being constants.
The general formula for a quadratic function is shown below:
The symbols a,b,c are all parameters and the symbol x is a variable.
Changing x takes you to different points on a quadratic function. If you make a change to a, b or c then you have a different quadratic function.
Rob Sterling 