The fundamentals of distribution theory are developed. The Dirac impulse is introduced motivated with a circuit that causes a derivation of an input signal. Starting from this example, the space of distributions is defined and examples of its elements are given. Such elements are, for example, all locally integrable functions, the principal value, and other pseudofunctions like rational functions or 1/—t—. The calculus of distributions is developed to the extent as necessary in the further text. This includes generalized derivatives and convolution of distributions. The results are generalized for multidimensional parameters and test functions over the complex scalar field. Examples for every topic and exercises complete the chapter.