The <strong>/<b> and <em>/<i> tags have exactly the same effect in most web browsers, but there is a fundamental difference between them: <strong> and <em> have a semantic meaning whereas <b> and <i> only convey styling information like CSS.

When <b> can have simply no effect on a Palm device with limited display or when a screen reader software is used by a blind person, <strong> will:

Consequently:

Noncompliant Code Example

<i>car</i>                 <!-- Non-compliant -->
<b>train</b>               <!-- Non-compliant -->

Compliant Solution

<em>car</em>               <!-- Compliant -->
<strong>train</strong>     <!-- Compliant -->