Book excerpt: Currently, most of the major commercial metal additive manufacturing (MAM) techniques rely on liquid phase processing. The liquid to solid phase transformations in these techniques results in microstructural issues and defects which in turn tantamount to inferior properties of fabricated build. Friction based additive manufacturing technologies are solid state processing techniques which work on the principles of friction based joining processes and layer by layer additive manufacturing. This book primarily addresses the basic understanding of seven friction based additive manufacturing techniques. These techniques include additive manufacturing methods based on rotary friction welding, linear friction welding, friction deposition, friction surfacing, friction stir additive manufacturing, friction assisted seam welding and additive friction stir. The principle of operations, benefits, limitations and recent developments of each technique has been described. It covers potentional and probable applications of each technique through review of various experimental studies. Features Targets friction based solid state additive manufacturing of metallic materials Describes principle of operation of seven friction based additive manufacturing techniques Reviews latest trends of these processes via experimental studies Describes benefits and limitations of each technique Covers current and probable applications of these techniques