It could be that the primary typeface doesn’t offer enough variation, perhaps being limited in the number of weights, widths, or styles—which could be as simple as not having a different weight to use as a heading. Some typefaces don’t have italics, so rather than have italic text rendered as a faux italic, we could choose a secondary typeface to use instead.
Arial Font is used as the backup font of Proxima Nova, would be used only if Proxima Nova font is not available in the system.
Arial Regular
Arial Medium
Arial Bold
Arial Extra Bold
Body copy set in proxima nova regular, sentence case. Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.