What role do typography, line length, and line-height play in UI readability?

• A. Ensure comfortable reading; optimal line length 45-75 characters; appropriate line-height.
• B. Use extremely long lines to maximize content.
• C. Ignore line-height for readability.
• D. Use small fonts to fit more content.

Answer: (A)

The way text looks and flows on a screen directly affects how easily people can read and understand it. Typography sets up readable character shapes and contrast, while line length and line-height control how the eye moves from one line to the next. For comfortable reading, aim for a line length in roughly 45 to 75 characters per line; lines that are too short cause choppiness, and lines that are too long force the eye to wander and lose track. Line-height, the vertical space between lines, should be enough to prevent lines from feeling crowded but not so loose that text reads as disjointed; a typical range is about 1.4 to 1.6 times the font size. Together, these choices reduce eye strain and improve comprehension, especially for UI where users skim and scan content quickly. The other approaches—making lines extremely long, ignoring line-height, or shrinking font size to fit more text—make reading harder, increase fatigue, and hurt usability.