Inline text elements like strong, em, mark and code, and the difference between meaning and looks.
Modern HTML separates the meaning of text from its presentation. <strong> signals strong importance and <em> signals stress emphasis, while <b> and <i> are purely stylistic offsets that carry no extra importance. Other inline elements add meaning too: <mark> highlights relevance, <code> and <pre> represent code, <abbr> expands abbreviations, <time> gives machine-readable dates, and <sub>, <sup>, <small>, <del> and <ins> handle specific text conventions.
The classic question is 'what's the difference between <strong> and <b>?' The visual result is usually identical, but strong conveys importance to browsers, search engines and screen readers, while b doesn't. Another point worth knowing is that browsers collapse consecutive whitespace and line breaks in normal text, which is why <pre> exists to preserve them. Picking elements for their meaning, then styling with CSS, is the habit being tested.
What you'll walk away knowing