<em>
HTML <em> Tag
The <em> tag specifies a text that has stress emphasis. Browsers display the text within this 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 is considered to be a phrase tag, which points out that a section of the text has a structural meaning.
Syntax
Syntax （语法）
The <em> tag comes in pairs. The content is written between the opening (<em>) and closing (</em>) tags.
Example of the HTML <em> tag:
<!DOCTYPE html>
<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>
Result
The difference between the <em> and the <i> tags
The difference between the <em> and the <i> tags
The <em> and <i> tags are usually confused, because they create similar results because both of them italicize the text. However, the results are the same only visually. The <em> element specifies the text that has stress emphasis, while the <i> tag defines a part of the text in a different voice. It is usually used to define technical terms, phrases from foreign languages, etc.
Attributes
Attributes （属性）
The <em> tag supports the Global Attributes and the Event Attributes.
How to style <em> tag? Common properties to alter the visual weight/emphasis/size of text in <em> tag:
CSS font-style property sets the style of the font. normal | italic | oblique | initial | inherit. CSS font-family property specifies a prioritized list of one or more font family names and/or generic family names for the selected element. CSS font-size property sets the size of the font. CSS font-weight property defines whether the font should be bold or thick. CSS text-transform property controls text case and capitalization. CSS text-decoration property specifies the decoration added to text, and is a shorthand property for text-decoration-line, text-decoration-color, text-decoration-style.
Coloring text in <em> tag:
CSS color property describes the color of the text content and text decorations. CSS background-color property sets the background color of an element.
Text layout styles for <em> tag:
CSS text-indent property specifies the indentation of the first line in a text block. CSS text-overflow property specifies how overflowed content that is not displayed should be signalled to the user. CSS white-space property specifies how white-space inside an element is handled. CSS word-break property specifies where the lines should be broken.
Other properties worth looking at for <em> tag:
CSS text-shadow property adds shadow to text. CSS text-align-last property sets the alignment of the last line of the text. CSS line-height property specifies the height of a line. CSS letter-spacing property defines the spaces between letters/characters in a text. CSS word-spacing property sets the spacing between words.