There are undoubtedly many motivations for writing books. But what determines the choice of a topic? Knowledge and preferences certainly play a role, but there must also be the conviction that the subject matter is significant not only for the authors. This is how we feel about "Parallel Processing." Individual reasons for this are outlined in the book; in short, we believe that an encounter with it is unavoidable and that at least some of its principles deserve sufficient interest. Therefore, we have written an introduction aimed at providing a gateway into this field. From the perspective of recognizing certain (simple) classes of patterns, the first part introduces various models of automata that represent different modes of parallel processing.