Integration by substitution is one of the basic methods of integration. An integral of the type [br][math]\int g'\left(x\right)f\left(g\left(x\right)\right)dx[/math][br]is an example where this method may be applicable. Sometimes using substitution [math]t=g\left(x\right)[/math] may convert the integral to a form suitable for another method. Purpose of this applet is to facilitate practice of the method of integration by substitution.