HTML id Attribute


Use the id attribute to manipulate text with JavaScript:


<h1 id="myHeader">Hello World!</h1>
<button onclick="displayResult()">Change text</button>

function displayResult() {
    document.getElementById("myHeader").innerHTML = "Have a nice day!";

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More "Try it Yourself" examples below.

Definition and Usage

The id attribute specifies a unique id for an HTML element (the value must be unique within the HTML document).

The id attribute is most used to point to a style in a style sheet, and by JavaScript (via the HTML DOM) to manipulate the element with the specific id.

Browser Support

id Yes Yes Yes Yes Yes

Differences Between HTML 4.01 and HTML5

In HTML5, the id attribute can be used on any HTML element (it will validate on any HTML element. However, it is not necessarily useful).

In HTML 4.01, the id attribute cannot be used with: <base>, <head>, <html>, <meta>, <param>, <script>, <style>, and <title>.

Note: HTML 4.01 has greater restrictions on the content of id values (for example; in HTML 4.01 id values cannot start with a number).


<element id="id">

Attribute Values

Value Description
id Specifies a unique id for the element. Naming rules:
  • Must contain at least one character
  • Must not contain any space characters
  • In HTML, all values are case-insensitive

More Examples

Example 1

Use the id attribute to link to an element with a specified id within a page:


<h2><a id="top">Some heading</a></h2>

<p>Lots of text....</p>
<p>Lots of text....</p>
<p>Lots of text....</p>

<a href="#top">Go to top</a>

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Example 2

Use the id attribute to style text with CSS:

#myHeader {
    color: red;
    text-align: center;

<h1 id="myHeader">W3Schools is the best!</h1>

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Related Pages

HTML Tutorial: HTML Attributes

CSS Tutorial: CSS Syntax

CSS Reference: CSS #id Selector

HTML DOM Reference: HTML DOM getElementById() Method

HTML DOM Reference: HTML DOM id Property

HTML DOM Reference: HTML DOM Style Object