<p>The <dd>focal length</dd> of a lens gives the distance from the lens to the image sensor.</p> Definition element => The <dfn> HTML element is used to indicate the term being defined within the context of a definition phrase or sentence.
**Description Term element => The <dt> HTML element specifies a term in a description or definition list, and as such must be used inside a <dl> element.
**Description Details element =>The <dd> HTML element provides the description, definition, or value for the preceding term (<dt>) in a description list (<dl>). Source