The <em> tag defines text that has stress emphasis. Browsers display the text within the tag in italic.
The <em> tag is an element of logical markup in contrast to the <i> tag, which has the same visual effect (italic), but at the same time, doesn’t carry a semantic load.
The <em> tag is not deprecated, but it is possible to achieve richer effects with CSS font-style property.
The <em> tag comes in pairs, so the content is written between the opening (<em>) and the closing (</em>) tags.
<html> <head> <title>Title of the document</title> </head> <body> <p>It is a normal paragraph</p> <p>The important part of the text is highlighted by the <em> in italic</em>.</p> </body> </html>