Why the Gap Between Lines Guides the Eye
Line spacing is the vertical distance from one line of text to the next. In typography, it is often called leading. That gap does more than make a page look airy: it helps the eye identify which line comes next.
Reading involves quick eye movements, not a smooth glide across the page. At the end of a line, the eyes jump back toward the left edge and down to the next one. If lines sit very close together, the next line can be harder to distinguish from the lines above and below. The eyes may land in the wrong place, forcing a reader to search for the sentence again.
Spacing Is a Balance, Not a Simple Fix
More space can make the next line easier to locate, but too much can weaken the sense that successive lines belong to the same passage. It also means fewer lines fit on a screen or page. Designers therefore balance legibility with the need to keep a paragraph visually connected and manageable.
The useful amount depends on the typeface, letter size, line length, and reading conditions. A large font or a long line may need different spacing from a small font in a narrow column. Good line spacing gives the eye a clear landing point without making each line feel isolated. That is why adjusting the gap can make the same words feel easier—or harder—to follow.
