Technically speaking, any webpage should be able to display any font, assuming said font is installed on the person who is trying to view that webpage's computer. A computer can't display a font unless that font is installed on their computer. It's fairly safe to assume most people have
these fonts installed, but you can never be 100% sure, which is why most people, when writing the CSS for their webpages, make sure to include listed "backup" fonts, in case their first choice isn't available.