Column

A vertical field the text is poured into. Its width is a reading decision: too wide and the eye loses its way back.

A column is a promise about line length. The comfortable measure runs somewhere near forty five to seventy five characters; beyond that the eye finishes a line and cannot find its way back, beneath it the text breaks into stutter. Column width is a reading decision dressed as a layout decision.

This is why our text columns stop well short of the screen's width, whatever the screen. A wide viewport earns wider margins and more air, not longer lines. Multiple columns split the measure honourably, but on scrolling surfaces one good column usually beats two cramped ones.