HTML rp element

The <rp> HTML element is used to provide fall-back parentheses for browsers that do not support display of ruby annotations using the <ruby> element. One <rp> element should enclose each of the opening and closing parentheses that wrap the <rt> element that contains the annotation’s text.

Ruby annotations are for showing pronunciation of East Asian characters, like using Japanese furigana or Taiwanese bopomofo characters. The <rp> element is used in the case of lack of <ruby> element support; the <rp> content provides what should be displayed in order to indicate the presence of a ruby annotation, usually parentheses.