The study of noncommutative rings is a major area in modern algebra. The structure theory of noncommutative rings was originally concerned with three parts: The study of semi-simple rings; the study of radical rings; and the construction of rings with given radical and semi-simple factor rings. Recently, this has extended to many new parts: The zero-divisor theory, containing the study of coefficients of zero-dividing polynomials and the study of annihilators over noncommutative rings, that is related to the Koethe's conjecture; the study of nil rings and Jacobson rings; the study of applying ring-theoretic properties to modules; representation theory; the study of relations between algebraic and concepts of other branches (for example, analytic and topological), etc. Thus, noncommutative rings are ubiquitous in mathematics, and occur in numerous sciences.This volume consists of a collection of original articles refereed by world experts that was presented at the Sixth China-Japan-Korea International Conference on Ring Theory. These articles exhibit new ideas, tools and techniques needed for successful research and investigation in noncommutative ring theory, and show the trend of current research. It is a useful resource book for beginners and advanced experts in ring theory.