Ink is fundamentally a fluid or paste composed of colorants—which can be pigments (insoluble particles) or dyes (soluble compounds)—suspended in a liquid vehicle. The choice of composition dictates the ink's permanence, drying speed, and application method. Historically, inks utilized varied organic materials, while modern formulations often rely on stable synthetic dyes and carbon compounds suspended in carriers such as water, alcohol, or oils. The binding agents and chemical interactions between the ink and the substrate determine the resulting bond, ranging from surface adhesion to chemical bonding with the porous material. This technological application is essential for the creation of durable records, graphical markings, and industrial labeling, making it a foundational element of written communication and scientific notation.