Font
A font is a specific implementation of a typeface, meaning it includes a particular style (like bold or italic), weight, and size.
For example, Helvetica Bold 12pt is a font (a specific style, size, and weight of the Helvetica typeface).
Early fonts were individual sets of metal types that were handset to print pages. Since they were cast in metal, each size and weight necessitated a separate set of characters called sorts.