The em element is one of a large group of elements that the HTML 4 recommendation calls phrase elements. Such elements assign structural meaning to a designated portion of the document. An em element is one that is to be rendered differently from running body text to designate emphasis.

Browsers have free rein to determine how (or whether) to distinguish em element content from the rest of the body element. Both Navigator and Internet Explorer elect to italicize the text. Override the default with a style sheet as you see fit.

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.