To keep up with the pace of Industry 4.0, Metal Additive Manufacturing(MAM) is revolutionizing its course from fusion-based MAM to the recently developed Solid State Friction Stir MAM. Fusion-based MAM has numerous drawbacks, especially due to solidification issues and inferior shear strength. Friction Stir Additive Manufacturing (FSAM) has variant novel techniques, it works on the governing principle of Friction Stir Welding (FSW) to build components layer after layer. Friction Stir Deposition is a very recent development in which the feed material, which is in form of powder, rod, or in form of machine chips (recycled) sustains in situ self-generated heating (by Friction stir mechanism).Due to the development of high strain rates, the feedstock binds to the substrate by extensive global plastic deformation leading to dynamic recrystallization giving fully dense bindings without any porosity, hot cracks, and inclusions. Being a solid-state thermo-mechanical process, it overcomes the drawbacks of Binder Jetting, Direct Energy Deposition, Sheet Lamination, and other MAM Techniques by giving, not only defect-free but also a microstructure, which is even better than the wrought, superior mechanical and structural properties, tight tolerances, proper bindings locally as well as globally, but lacks the ability for excessively complex parts. Owing to equiaxed and uniform refined microstructure, high energyefficiency, scalability, a wide range of material (Al, Ti, Ni, Mg) usage, reduced part distortion, its ease of use, superior quality, variety in feed materials, and minimal post-processing needed, it is amongst the best suited MAM for industries like aerospace, automotive, military, biomedical and maritime which require to manufacture high-strength, low-weight pure bulk metals, laminates, composites, biocomposites, alloys, and coatings. This paper outlines the mechanism of various FSAM techniques, studies the Process Parameters, the scope of Material Flexibility, defect detection, and the difficulties involved in enhancing the microstructure and efficiency. The paper concludes by analyzing its future trends