A classic introduction to group theory for nearly a century, this is the book most often cited in texts on group theory for detailed expositions of basic concepts.After introducing permutation notation and defining group, the author discusses the simpler properties of group that are independent of their modes of representation; composition-series of groups; isomorphism of a group with itself; Abelian groups; groups whose orders are the powers of primes; and Sylow's theorem. Permutation groups and groups of linear substitutions receive an extensive treatment; two chapters are devoted to the graphical representation of groups, and the closing chapter to congruence groups. Forty-five pages of notes at the back of the book offer ample treatment of special topics.