Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In the mathematical subject of group theory, small cancellation theory studies groups given by group presentations satisfying small cancellation conditions, that is where defining relations have small overlaps" with each other. It turns out that small cancellation conditions have substantial implications for algebraic, geometric and algorithmic properties of the group. Finitely presented groups satisfying sufficiently strong small cancellation conditions are word hyperbolic and have word problem solvable by Dehn''s algorithm. Small cancellation methods are also used for constructing Tarski monsters, and for solutions of Burnside''s problem."