# HTML5

#### 4.6.12 The
`var`

element

- Categories:
- Flow content.
- Phrasing content.
- Palpable content.
- Contexts
in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Content attributes:
- Global attributes
- DOM
interface:
- Uses
`HTMLElement`

.

The `var`

element represents
a variable. This could be an actual variable in a mathematical
expression or programming context, an identifier representing a
constant, a symbol identifying a physical quantity, a function
parameter, or just be a term used as a placeholder in prose.

In the paragraph below, the letter "n" is being used as a
variable in prose:

<p>If there are <var>n</var> pipes leading to the ice
cream factory then I expect at <em>least</em> <var>n</var>
flavors of ice cream to be available for purchase!</p>

For mathematics, in particular for anything beyond the simplest
of expressions, MathML is more appropriate. However, the
`var`

element can still be used to refer to
specific variables that are then mentioned in MathML
expressions.

In this example, an equation is shown, with a legend that
references the variables in the equation. The expression itself is
marked up with MathML, but the variables are mentioned in the
figure's legend using `var`

.

<figure>
<math>
<mi>a</mi>
<mo>=</mo>
<msqrt>
<msup><mi>b</mi><mn>2</mn></msup>
<mi>+</mi>
<msup><mi>c</mi><mn>2</mn></msup>
</msqrt>
</math>
<figcaption>
Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of
a triangle with sides <var>b</var> and <var>c</var>
</figcaption>
</figure>

Here, the equation describing mass-energy equivalence is used in
a sentence, and the `var`

element is used to mark the variables and
constants in that equation:

<p>Then he turned to the blackboard and picked up the chalk. After a few moment's
thought, he wrote <var>E</var> = <var>m</var> <var>c</var><sup>2</sup>. The teacher
looked pleased.</p>