They are part of the changes to the WHATWG HTML specification, so it's not just Mozilla. MDN is just reflecting/documenting what is in the different standards.

They are part of the changes to the WHATWG HTML specification, so it's not just Mozilla. MDN is just reflecting/documenting what is in the different standards. From https://html.spec.whatwg.org/multipage/text-level-semantics.html#the-b-element https://html.spec.whatwg.org/multipage/text-level-semantics.... (with _ added for the relevant section used by MDN): > The b element represents a span of text _to which attention is being drawn_ for utilitarian purposes without conveying any extra importance and with no implication of an alternate voice or mood, such as key words in a document abstract, product names in a review, actionable words in interactive text-driven software, or an article lede. From https://html.spec.whatwg.org/multipage/text-level-semantics.html#the-i-element https://html.spec.whatwg.org/multipage/text-level-semantics.... (with _ added for the relevant section used by MDN): > The i element represents a span of text in an alternate voice or mood, or otherwise offset from the normal prose in a manner indicating a different quality of text, such as a taxonomic designation, a technical term, _an idiomatic phrase_ from another language, transliteration, a thought, or a ship name in Western texts.