A definition list is an HTML list used to display a series of terms along with their corresponding definitions or descriptions. It is created using the <dl> tag, while the <dt> tag defines the term and the <dd> tag provides its description.
<dl>
<dt><strong>HTML</strong></dt>
<dd>HTML is Hypertext Markup Language.</dd>
<dt><strong>CSS</strong></dt>
<dd>CSS is Cascading Style Sheet.</dd>
</dl>