Nowadays, the terms "typeface" and "font" are often used interchangeably, but it has not always been the case. The blurred distinction between the two terminologies is a reminder that the industry changes gradually over time. However, at a technical level, they do have distinctions and should be used correctly by designers.

A typeface

A typeface is a set of glyphs (including alphabet, numerals, punctuations, symbols, etc.) that share common design features. For example, Helvetica and Arial are two popular typefaces.

Figure 1. Noto Sans typeface

A font

Historically, a "font" is used to is a set particular subset of glyphs within a typeface of particular style and style. For example, Helvetica Bold 14pt is a font. The word "font" is used to addressed the metal casted pieces, stored in shallow wooden drawers, to be used by a typesetter.

2880px-Lead_type_case_(25598835882)-1.jpeg

Figure 2. Lead type case (photograph by Thom Quine at Wikipedia, distributed under a CC-BY 2.0 license)

After the rise of digital publishing, the term gets muddied. Nowadays, a "font" is referred to the single set of glyphs included within a font file (.otf, .ttf). For example, Helvetica Bold or Arial Black. A group of font files of the same typeface design is called a "font family".

Figure 3. The glyphs within Noto Sans (Regular) font, stored in a .TTF format file.

So what's the difference, basically?

In short, a font is what you use, a typeface is what you see. Typographer Nick Sherman suggested the distinction like this: "The way I relate the difference between typeface and font to my students is by comparing them to songs and MP3s, respectively (or songs and CDs, if you prefer a physical metaphor)."

When you address the design of the set of type, you would use "typeface" and you would use "font" to talk about the software usage of the typeface. Finally, please refer to the designers who design typefaces (and fonts) as "typeface designers" or "type designers", not "font designers."