id HTML Attribute

The "id" attribute in HTML is used to define a unique identifier for an element. The value of the attribute must be unique within the HTML document and it can be used to target the element with CSS or JavaScript.

For example, in the following code snippet, the id attribute is set to "unique-id" for a div element:


<div id="unique-id">This is a div element with a unique id</div>

In CSS, you can use the "#" symbol followed by the id value to target the element with that id and apply styles to it.


#unique-id {
  background-color: blue;
}

In JavaScript, you can use the getElementById() method to target the element with that id and manipulate it or retrieve its properties.


let element = document.getElementById("unique-id");
element.innerHTML = "new content";

It's worth noting that the id attribute is widely supported by all modern browsers, and also it is a standard attribute, which means it is part of the official HTML specification. Also, the value of the id attribute should be unique within the HTML document, if not, it could lead to unexpected behavior.

In summary, the "id" attribute in HTML is used to define a unique identifier for an element. The value of the attribute must be unique within the HTML document and it can be used to target the element with CSS or JavaScript. It is widely supported and is a standard attribute, which means it is part of the official HTML specification. It is important that the value of the id attribute should be unique within the HTML document to avoid unexpected behavior.