The book is dedicated to linguistic morphology; it contains a sketch of a complete morphological theory, centered around a discussion of such fundamental concepts as morph vs. morpheme, inflectional category, voice, grammatical case, agreement vs. government, suppletion, relationships between linguistic signs, etc.: the hottest issues in modern linguistics. The book introduces rigorous and clear concepts necessary to describe morphological phenomena of natural languages; among other things, it offers logical calculi of possible grammemes in a given category. The presentation is developed in a typological perspective, so that linguistic data from a large variety of languages are described and analyzed (about 100 typologically very different languages). The main method is deductive: the concepts proposed in Aspects of the Theory of Morphology are based on a small set of indefinibilia and each concept is defined in terms of these indefinibilia and/or other concepts defined previously; as a result, logical calculi can be constructed (similar to Mendeleev’s Periodical Table of Elements in chemistry). Then the concept is applied to the actual linguistic data to demonstrate its validity and advantages. Thus, Aspects of the Theory of Morphology combines metalinguistic endeavor (a system of concepts for morphology) with typological and descriptive orientation. It reaches out to all students of language, including the border fields and applications.