A font (more accurately a typeface) is the graphic representation of characters and the software that manages or configures writing systems.
Typefaces are sets of alphanumeric characters, punctuation, and often other symbols as well. These can typically be customized to a limited extent, with parameters such as style (e.g. italic, bold), size (e.g. 13pt), and color. The combination of the typeface plus these settings is known as a font.
In today's culture, font can also be used to refer to typefaces, and vice versa.