Any single continuous line, whether straight or curved, that forms part of a letterform. Every Glyph is constructed from one or more strokes: Stem, Bowl, arms, crossbars, tails, and Terminal are all specialized stroke types. Stroke Weight (thickness) and stroke contrast (the ratio between the thickest and thinnest strokes within a design) are two of the most consequential variables in Typeface classification and Readability.