Variable [fonts](/glossary/font)—or, more specifically, [OpenType](/glossary/open_type) Font Variations—are a relatively new font [format](/glossary/font_format) that allow one font file to contain multiple stylistic variations. [Weight](/glossary/weight), [width](/glossary/width), [style](/glossary/style), [optical size](/glossary/optical_sizes), etc. can then be manipulated by the end user (i.e., designer) and thus avoid the strict delineations of “traditional” fonts.

<figure>

![Three different examples of “Aa”, each with a their variable axes adjusted. The first has a light weight and body-like optical size; the second has a heavy weight and display-like optical size (with a higher stroke contrast); the third also has a similarly heavy weight, but with a body-like optical size.](images/thumbnail.svg)
<figcaption>The first example has a light weight and body-like optical size; the second has a heavy weight and display-like optical size (note the higher contrast); the third also has a similarly heavy weight, but with a body-like optical size.</figcaption>

</figure>

There are two main benefits offered by variable fonts:

1. The unified delivery of multiple [instances](/glossary/instance)—such as different weights, widths, optical sizes—in a single font file that is much smaller than a collection of individual font files.
2. The control given to the user to select values in between the traditional definitions for weight, width, etc.

The variables within variable fonts are controlled by [axes](/glossary/axis_in_variable_fonts) or instances. If the type designer, chooses, any variable in the type design can be assigned to a user-controllable axis.