Digital printing technology has significantly impacted the textile and graphic industries, empowering high-quality, efficient, customizable printing solutions. At the core of this impact is the ink, which plays a crucial role in analyzing and determining the quality, durability, and sustainability of the final output. The ink’s chemistry and formulation also determine the jetting characteristics and printing quality. The raw materials in digital ink, including pigments, binders, solvents, and additives, are specifically designed to work with different substrates and printing techniques, establishing the significance of their roles in these industries. This chapter deals with inks, their technology in the digital printing industry, and how it critically influences prints, including a comparative study of different digital printing methods. This study also examines the classifications and uses of different ink-jet technologies, focusing mainly on ink-jet technology because of its dependability and compatibility with a wide range of inks. The various types of inks used in digital printing are discussed briefly, along with how different ink parameters influence their capability in the digital printing industry. Textile printing has been largely influenced by digital printing technology, with good results in print speed, print head technology, and colour gamut. This chapter also provides an overview of the fluid dynamics of ink-jet printing. These consider the wetting phenomena at the nozzle plate, jet generation, the meniscus dynamics, the flow details of the print head and on reaching the substrate side, the droplet impact, merging, wetting of the substrate, followed by droplet evaporation and drying at the end.