What is truth? Although this question is almost as old as philosophy itself, it has not lost much of its attractiveness, it has been present during the whole history of philosophy. One easily recognizes that philosophers starting with Aristotle up to the 21. Century came up with various theories of truth in the hope of clarifying this enigmatic concept. Even if a certain progress concerning this subject-matter is recognizable, a solid agreement is still missing. However, if one restricts the question >, What is truth?<, to a limited branch of philosophy such as logic, one is able answer it without being forced to present conflicting theories. Franz Josef Rainer applies himself to the question >, What is the meaning of truth in logic?<, , which he tries to answer in a short and understandable manner. He goes into detail only if it is necessary for a proper understanding of the subject-matter. He refrains from the presentation of hardly comprehensible logical formulas and sticks to the field of elementary logic, which is taught in philosophy. Therefore, one need not be a professional logician in order to follow the thoughts, it is sufficient to be interested in this subject-matter.