Measure.- The Lebesgue Model.- Measurable Functions.- The Integral.- The Product Measure.- Change of Variables in an Integral.- Integrals Dependent on a Parameter.- Surface Integrals.- Approximation and Convolution of the Space.- Fourier Series and the Fourier Transform.- Charges. The Radon-Nikodym Theory.- Integral Representation of Linear Functionals.- Appendices.