Revision with unchanged content. In these days our daily life is more and more affected by computers. For this reason it is necessary to find a simple and intuitive way to interact with complex technologies. Natural language dialog systems could be the solution how humans and machines could communicate with each other. One of the main tasks of such dialog systems is to provide fast and appropriate answers to user’s questions. The challenge is: how do we find these answers out of the flood of information? Is there a way or an algorithm to find the appropriate answer to a given question? The author Christian Pretzsch gives, at first, an overview about the linguistically and theoretically background. Therein, among other things, the concepts: dialog, dialog systems, and ontology are introduced. Afterwards, answer selection and question-answering are elucidated, before the found results are tested for a concrete case study. This example and its evaluation is the base for an alternative approach. The illustrated algorithm could be a solution to realize answer selection in a fast and effective way. This book is addressed to students and all interested parties of Computational Linguistics, Computer Science, and Applied Linguistics.