Hot isostatic pressing (HIP) is widely used within the additive manufacturing (AM) industry to improve material performance and ensure quality. This article is a detailed account of the HIP process, providing information on its equipment set up and discussing the applications, economics, and advantages of the process. The discussion also covers the use of HIP for additively manufactured material to eliminate internal defects, the HIP parameters required to eliminate internal defects, and the influence of HIP on the microstructure and properties of HIP additively manufactured material.