HTML <sub> Tag

The <sub> tag is used to define the subscript text that appears half a character below the line and is rendered in a smaller font. The subscript text can often be used for defining chemical formulas.

You must use the <sub> tag only for typographical reasons. It shouldn’t be used for styling purposes. If you want to change the vertical position of a text, you can use the CSS vertical-align property with the "sub" value.

To define superscript text, use the <sup> tag.

Syntax

The <sub> tag comes in pairs. The content is written between the opening (<sub>) and closing (</sub>) tags.

Example of the HTML <sub> tag:

<!DOCTYPE html>
<html>
  <head>
    <title>Title of the document</title>
  </head>
  <body>
    <p>Formula of water - H<sub>2</sub>O,  formula of alcohol - C<sub>2</sub>H<sub>5</sub>ОН</p>
  </body>
</html>

Result

Example of the HTML <sub> tag used with the <sup> tag:

<!DOCTYPE html>
<html>
  <head>
    <title>Title of the document</title>
  </head>
  <body>
    <p>The formula of water is H<sub>2</sub>O,  and the formula of alcohol is C<sub>2</sub>H<sub>5</sub>ОН </p>
    <p>E = mc<sup>2</sup>, where E — kinetic energy, m — mass, c — the speed of light. </p>
  </body>
</html>

Example of the HTML <sub> tag used with the CSS vertical-align property:

<!DOCTYPE html>
<html>
  <head>
    <title>Title of the document</title>
    <style>
      sub{
      vertical-align: sub; 
      font-size: small; 
      }
    </style>
  </head>
  <body>
    <h1>Example of the sub tag</h1>
    <p>
      Here is some text <sub>with the sub tag</sub>.
    </p>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis ...</p>
    <p>Reference site about Lorem Ipsum,<sub> giving information on its origins</sub>, as well as a random Lipsum generator.</p>
  </body>
</html>

Attributes

The <sub> tag supports the Global attributes and the Event Attributes.

How to style <sub> tag?

Common properties to alter the visual weight/emphasis/size of text in <sub> 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 <sub> 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 <sub> 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 <sub> tag:


Browser support



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