<rb>: The Ruby Base element


This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The HTML Ruby Base (<rb>) element is used to delimit the base text component of a  <ruby> annotation, i.e. the text that is being annotated. One <rb> element should wrap each separate atomic segment of the base text.

Content categories None.
Permitted content As a child of a <ruby> element.
Tag omission The end tag can be omitted if the element is immediately followed by an <rt><rtc>, or <rp> element or another <rb> element, or if there is no more content in the parent element.
Permitted parents A <ruby> element.
Permitted ARIA roles Any
DOM interface HTMLElement


This element only includes the global attributes.

Usage notes

  • Ruby annotations are for showing pronunciation of East Asian characters, like using Japanese furigana or Taiwanese bopomofo characters. The <rb> element is used to separate out each segment of the ruby base text.
  • Even though <rb> is not an empty element, it is common to just include the opening tag of each element in the source code, so that the ruby markup is less complex and easier to read. The browser can then fill in the full element in the rendered version.
  • You need to include one <rt> element for each base segment/<rb> element that you want to annotate.


In this example, we provide an annotation for the original character equivalent of "Kanji":


Note how we've included two <rb> elements, to delimit the two separate parts of the ruby base text. The annotation on the other hand is delimited by two <rt> elements.

Note that we could also write this example with the two base text parts annotated completely separately. In this case we don't need to include <rb> elements:


The output looks like so:

The HTML above might look something like this when rendered by a browser without ruby support:

Note: See the article about the <ruby> element for further examples.


Specification Status Comment
The definition of '<rb>' in that specification.

Browser compatibility

BCD tables only load in the browser

See also