The b elementone of several font style elements in HTML 4renders its content in a boldface version of the font face governing the next outermost HTML container. You can nest multiple font style elements to create combined styles, such as bold italic (<B><I>bold-italic text</I></B>).

It is up to the browser to fatten boldface display by calculating the character weight or by perhaps loading a bold version of the currently specified font. If you are striving for font perfection, it is best to use style sheets (and perhaps downloadable fonts) to specify a true bold font family, rather than risk the browser's extrapolation of a boldface from a system font. The font-weight CSS style attribute provides quite granular control over the degree of bold applied to text if the font face supports such fine-tuning.

You can take advantage of the containerness of this element by assigning style sheet rules to some or all b elements in a page. For example, you may wish all b elements to be in a red color. By assigning the style rule b {color:red}, you can do it to all elements with only a tiny bit of code.

Although this element is not deprecated in HTML 4 or XHTML 1.0, it would not be surprising to see it lose favor to style sheets in the future.

The language being used for the element's attribute values and content. A browser can use this information to assist in proper rendering of content with respect to details such as treatment of ligatures (when supported by a particular font or required by a written language), quotation marks, and hyphenation. Other applications and search engines might use this information to aid the selection of spell-checking dictionaries and the creation of indices.