What Is Typeface?
A typeface is the design of a set of characters — the shapes of the letters, numbers, and symbols — sharing a consistent visual style. Helvetica and Garamond are typefaces. A typeface is the design; a font is one specific size, weight, or style of that design.
The word "typeface" predates digital design: it originally referred to the printing face of the metal type that pressed ink onto paper. Today it describes the intellectual design work — the proportions, the curves, the way each glyph relates to the next.
Designers distinguish a typeface (the family of related styles, like Garamond) from a font (a single deliverable, like Garamond Bold Italic at 12pt). In everyday speech the two words are used interchangeably, and on the web a "font file" usually contains an entire typeface family.