The 72 dpi standard originated in the 1980s with Apple’s first Macintosh computers. At that time, the Macintosh screen resolution was set to 72 pixels per inch (PPI - pixels per inch) to match the ImageWriter printer’s 144 dots per inch (DPI - dots per inch) output. This meant that what designers saw on the screen would print at the same physical size, creating a convenient one-to-one relationship between digital and print layouts. Over time, 72 dpi became the default reference for web images, even though modern screens now have much higher resolutions. Today, the number is more of a historical convention than a technical requirement, since digital image quality depends on pixel dimensions rather than dpi.