Font vs typeface
A typeface is the design. A font is one particular instance of it: a single weight and style, delivered as a file (or, originally, as a case of metal letters).
Typeface
Garamond
The whole design: its letter shapes, proportions and spirit, across every weight and style.
Font
Garamond Bold Italic
One member of that design, the thing you install, license and select: e.g. EBGaramond-BoldItalic.ttf.
Where the distinction comes from
In metal type, a font was a complete set of sorts of one typeface in one size and style, say, 10-point Caslon Roman. Printers bought fonts; foundries designed typefaces. The word comes from the Middle French fonte, “something melted”, because the letters were cast.
Digital type removed the size from the equation (one outline scales to any size), so today a font usually means one weight and style: a single file like Roboto-Medium.ttf. Variable fonts blur the line again by packing a whole range of weights into one file.
Why it can matter
- Licensing: licences are sold per font or per family, so “I need a licence for Gotham” may really mean four fonts.
- Identification: an identifier names the typeface; you then pick the font (weight and style) that matches your sample.
- Web performance: each font you load is another download, so choose only the weights you use.
Related: types of fonts, font weight, and the font identifier.
Questions people ask
Is Helvetica a font or a typeface?
Helvetica is a typeface (or type family). Helvetica Bold at 12 point, in metal type, was a font; today “Helvetica Bold” as a single file is a font.
Is it wrong to say font when I mean typeface?
Not in everyday use. Even type designers use “font” loosely, and operating systems call everything a font. The distinction matters mainly when you talk about licensing and files.
What is a font family?
A group of related fonts sharing one design, such as Regular, Italic, Bold and Bold Italic. Large families add widths (Condensed, Extended) and optical sizes.