Additive manufacturing proves more economical than traditional manufacturing processes like machining, forming, and casting in scenarios when design complexity is high, low-volume or single-unit production is required for research, development, and prototyping, and product customization is required. Moreover, additive manufacturing presents interesting avenues to improve sustainability and profitability in critical mineral industries like onsite repair, maintenance, and remanufacturing of damaged tools and parts, modular equipment parts, easy integration of sensors and devices into process equipment, and functionality improvements through improvisation and customization. This chapter introduces the fundamental principles of additive manufacturing and the different types of additive manufacturing processes including their standard ASTM terminologies. The unique benefits that set it apart from other manufacturing technologies are elaborated including aspects like design complexity and flexibility, topology optimization and generative design, functionally graded materials, advanced materials and metamaterials, on-site repair and remanufacturing, customization and economics of commercial production using additive manufacturing.