<rb>: The Ruby Base element

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 thought <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:

  漢 <rp>(</rp><rt>Kan</rt><rp>)</rp>
  字 <rp>(</rp><rt>ji</rt><rp>)</rp>

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
HTML Living Standard
The definition of '<rb>' in that specification.
Living Standard  
The definition of '<rb>' in that specification.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support5 No385155
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes No3815 Yes Yes

See also

Document Tags and Contributors

Contributors to this page: mfuji09, chrisdavidmills, fscholz
Last updated by: mfuji09,