<p>Friction Stir Additive Manufacturing (FSAM) is a new technology, which enables the production of high-performance metallic parts with higher structural integrity and lower levels of porosity compared to conventional additive manufacturing processes that rely on melting. This review paper gives detailed consideration of the FSAM process, particularly discussing the principles of operation, material systems used in the FSAM process, process parameters of FSAM process and the latest developments in FSAM. In this review paper, the effect of key parameters like tool rotation speed, traverse speed, probe geometry and deposition path on heat generation during processing, flow of material, evolution of microstructure and mechanical properties of fabricated parts will be discussed in detail. Moreover, developments in numerical modeling techniques like finite element and computational fluid dynamic modeling of thermal behaviour, residual stresses and material flow will be assessed. Challenges, such as oxide formation, residual stresses development, process parameter optimization and limitations of predictive simulation models as with any new technology are also associated with FSAM technology. The paper will conclude by highlighting the present research gaps and future directions in order to improve the process stability, material performance, and industrial scale-up capabilities of FSAM technology. Additionally, this review will discuss the potential of FSAM for producing functionally graded materials and multi-component materials for use in the aerospace and automotive industries.</p>