When it comes to marking up your document with bold and/or italicized text there is a bit of an argument about what tags to use. The W3C recommends using <strong> instead of <b> for making text bold and using <em> instead of <i> for making text italicized. Their reasoning is that <strong> and <em> tags both separate structure from style by placing some sort of meaning to the text inside those tags. Text inside the <em> tag is to be emphasized and text inside a <strong> tag is to be strongly emphasized. On the other hand, The <b> and <i> tags simply imply that the text should be displayed a different way. If you read the text inside the <b> or <i> tags you should not be reading them with any emphasis.

Matt Cuts, an employee of Google’s search engine team, noted in this video that Google had no preference between <b>/<i> and <strong>/<em>. So if you’re worried about SEO (search engine optimization) reasons for using the more semantic tags, don’t worry about it. However, I’ve put together a good checklist here to go over when you’re deciding which tag to use:

• <b>- Strictly a presentational element. If you want text to be bold but not have any semantic meaning.
• <strong> – Strictly a structural element. If you want text to be spoken with strong emphasis using a screen reader.
• <i> – Strictly a presentational element. If you want text to be italicized, but not have any semantic meaning.
• <em> – Strictly a structural element. If you want text to be spoken with emphasis using a screen reader.