What are CSS pseudo-classes?

  John Mwaniki /    Updated on 07 Jul 2024

As a web developer, you may have come across the term "pseudo-classes" or stuff like :focus, :hover, :last-child in CSS. If you're wondering what they are, this article will explain everything you need to know about CSS pseudo-classes.

What are CSS pseudo-classes?

CSS pseudo-classes are a way of selecting and styling elements based on their state or position in the document. They are indicated by a colon (:) followed by the pseudo-class name.

Syntax

selector:pseudo-class {
property: value;
}

The selector can be an HTML element, its class, or its Id attribute.

Below are some of the most commonly used pseudo-classes in CSS:

:hover

Used to select and style an element when the user hovers over it with their mouse cursor. For example, you can change the background color of a button when the user hovers over it:

button:hover {
  background-color: yellow;
}

Move Mouse Over Me!

:active

Used to select and style an element when it is being clicked or activated. For example, you can change the color of a link when the user clicks on it:

a:active {
  color: #F44336;
}

Click me!

:focus

Used to select and style an element when it receives focus. For example, you can change the border color of a text input field when the user clicks on it:

input:focus {
  border-color: green;
}

:first-child

Used to select and style the first child element of a parent element. For example, you can change the color of the first paragraph in a div element:

div p:first-child {
  color: purple;
}

:nth-child

Used to select and style an element based on its position among its siblings. For example, you can change the background color of the second paragraph in a div element:

div p:nth-child(2) {
  background-color: orange;
}

Or you can change the background color of every even row in a table:

tr:nth-child(even) {
  background-color: lightgray;
}

The above are just a few examples of CSS pseudo-classes. There are many more that you can use to create dynamic and interactive web pages.

Now you know what pseudo-classes in CSS are and what they are used for.