Because of continuous demand for more complexity in design and efficient use of materials, three-dimensional (3D) printing, commonly known as additive manufacturing (AM), has expanded exponentially in terms of application as well as development. The advantages of AM over conventional or subtractive manufacturing are very obvious at AM facilitates, where the creation of near-net-shaped components with reduced buy-to-fly ratio enables the production of complex designs. In the last couple of decades, there have been significant developments in the AM field and it has expanded in terms of new and wide range of materials, many incapable of production by other routes, often revealing enhanced mechanical properties for technologically strategic applications. The fundamental principle of AM technology is that a 3D model or design has been generated initially by using 3D computer-aided design (3D CAD), which can be fabricated without the requirement of process-planning directly, saving quite a lot of cycle time. Though this is not as simple as it sounds in general, AM technology significantly simplifies the production of complex 3D objects directly from the CAD data. This chapter explains the basic concepts of AM and describes the AM process from design to applications.