Baseline

The line every letter stands on. Align to it and a layout feels built; ignore it and the page never quite settles.

The baseline is the floor every letter stands on, and a baseline grid extends that floor through the whole page. When text in neighbouring columns shares the grid, lines align across the gutter and the spread reads as one built thing rather than adjacent accidents.

Holding the grid takes stubbornness: images, captions and headings all tempt the text off its floor. We size vertical space in multiples of the baseline so everything lands back on it. Pages set this way feel quietly engineered, and no reader will ever tell you why.