The spine is the central curved stroke of the “S”, running diagonally through the letter to connect its two rounded parts. It is the backbone of the “S”, and one of the most delicate strokes to draw in an alphabet.
Where to see it
The spine is visible at the center of the capital “S” and the lowercase “s”, in the part that slants down from the upper curve to the lower curve. Its thickness and angle vary greatly from one typeface to another.
Why this detail matters
The design of the spine directly shapes the balance and personality of a typeface:
- The spine often holds the thickest part of the “S”, making it a marker of a font’s contrast between thick strokes and hairlines;
- Its angle and curvature determine the balance of the letter: a spine that is too flat or too steep makes the “S” look unbalanced;
- Because the “S” is one of the hardest letters to draw, the quality of its spine is often a sign of the care put into the typeface as a whole.
Related term
The axis is the imaginary line that runs through the thinnest parts of a rounded letter, and it can also be read in the orientation of the spine of the “S”.
Anatomy glossary
Ascender, Descender, Sidebearing, Joint, Axis, Bar, Beak, Bowl, Loop, Set width, Counter, Serif, Stem, Leg, Minim, Baseline, Eye, Belly, Foot, Point, Tail, Cross stroke, Terminal; X-height, X-height, Cap height, Body; Mean line, Ear, Spur, Ball terminal, Ligature, Apex, Vertex, Arm, Shoulder, Spine, Em dash, Thick stroke, Hairline, Bracket, Bounding box