HTML: The strong and em tags

The <strong> and <em> tags are used for emphasizing parts of a text. The <strong> tag should be used to indicate strong importance, seriousness, or urgency, like to indicate key phrases in a text for someone skimming it. The <em> tag should be used to represent stress emphasis, like when you'd read the emphasized text in a different tone of voice. Both tags can be used together, where it makes sense.