In modern usage, with the advent of digital typography, ''font'' is frequently synonymous with ''typeface''. In particular, the use of ''vector'' or ''outline'' fonts means that different sizes of a typeface can be dynamically generated from one design. Each style may still be in a separate ''font file''--for instance, the typeface ''Bulmer'' may include the fonts ''Bulmer roman'', ''Bulmer italic'', ''Bulmer bold'' and ''Bulmer extended''--but the term ''font'' might be applied either to one of these alone or to the whole typeface.

a font is a set of characters of a certain design?
yes