How one font file spans many weights
A conventional font family often stores each weight—such as light, regular, and bold—as a separate font file. A variable font instead includes a range of designs and instructions for generating the intermediate shapes. Its weight axis, commonly labeled `wght`, lets software request a value between the font’s lightest and heaviest settings.
The type designer defines how letterforms change across that range. A stroke may grow thicker, but the design also has to preserve details such as the shape of a counter—the enclosed space inside letters like “o”—and the spacing between characters. The font’s interpolation data tells the rendering software how to move between the defined designs. The result is not a collection of separately stored files; it is a continuously adjustable design within the axis’s supported limits.
Why the range matters
A web page can ask for a specific weight instead of choosing only from a few preset steps. That makes it possible to tune emphasis more subtly, or to adjust text weight as part of a responsive design. The browser still needs a font that includes the requested axis and range; a variable font cannot generate weights outside its design limits.
“Continuous” describes the available settings, not an endless number of distinct visible outcomes: screens and software render at finite precision. The practical change is that a designer can choose a weight between familiar labels like regular and bold without loading a separate font file for every step.
