A dummy variable is a placeholder variable used in integration to represent the variable of integration. It has no impact on the final value of the definite integral.
Definite Integral: Represents the signed area under a curve within a specified interval.
Substitution: A method used in integration that involves changing variables to simplify an integral.
$\int_{a}^{b} f(x) \, dx$: Notation for a definite integral which calculates the area under function $f(x)$ from $a$ to $b$.