If the text's meaning is semantically strong, use the strong
element. If not, use a semantic named class (one that clearly shows the meaning of the element, don't mix presentation and data by calling it bold
etc) and reference it in your CSS.
<span class="important-message">I'm important!</span>
.important-message {
font-weight: bold;
}
Some people still use the b
element as a presentational hook, but it hasn't been deprecated, though most people favour the strong
element nowadays. Just make sure they are used correctly.