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What is Transition in CSS?

CSS transitions are a powerful tool that web developers can use to create smooth and visually appealing animations on their websites. They allow you to change the appearance of an HTML element over a specified duration, giving the user a sense of interaction and engagement. In this blog post, we'll explore the basics of CSS transitions, how to use them, and some practical examples to help you get started.

Understanding CSS Transitions

Imagine you're at a party and the DJ suddenly changes the music from a slow, soothing track to an upbeat, energetic one. The abrupt change can be jarring, and it might take some time for the guests to adjust to the new mood. This is similar to how a sudden change in the appearance of a webpage element can be jarring for users.

CSS transitions can help you avoid this abruptness by gradually changing the appearance of an element over a specified duration. This can make the change feel more natural and less sudden, giving your users a more pleasant experience.

How CSS Transitions Work

To create a CSS transition, you'll need to define two things: the property you want to animate and the duration of the animation. You can also specify an optional timing function to control the pace of the transition, and a delay before the transition starts.

Here's the general syntax for creating a CSS transition:

selector {
  transition-property: property;
  transition-duration: duration;
  transition-timing-function: timing-function;
  transition-delay: delay;

You can also use the shorthand transition property to define all four values at once:

selector {
  transition: property duration timing-function delay;

Now let's break down each of these properties.

Transition Property

The transition-property specifies the CSS property you want to animate. For example, if you want to animate the width of an element, you would set transition-property: width;.

Some common properties you can animate include:

  • width
  • height
  • background-color
  • opacity
  • transform

You can also use the keyword all to animate all animatable properties at once.

Transition Duration

The transition-duration property specifies how long the transition should take, usually in seconds (s) or milliseconds (ms). For example, transition-duration: 2s; would create a two-second-long transition.

Transition Timing Function

The transition-timing-function property allows you to control the pace of the transition. Some common values include:

  • linear: The transition progresses at a constant pace from start to finish.
  • ease: The transition starts slowly, accelerates in the middle, and slows down at the end (default).
  • ease-in: The transition starts slowly and accelerates.
  • ease-out: The transition starts quickly and decelerates.
  • ease-in-out: The transition starts slowly, accelerates, and then decelerates.

You can also create a custom timing function using cubic-bezier(x1, y1, x2, y2).

Transition Delay

The transition-delay property allows you to specify a delay before the transition starts, in seconds (s) or milliseconds (ms). For example, transition-delay: 1s; would create a one-second delay before the transition begins.

Practical Examples

Now that we understand the basics of CSS transitions, let's look at some practical examples.

Example 1: Hover Effect

In this example, we'll create a simple hover effect that changes the background color of a button when the user hovers over it.


<button class="btn">Hover Over Me</button>


.btn {
  background-color: blue;
  color: white;
  padding: 10px;
  cursor: pointer;
  transition: background-color 0.5s ease-in-out;

.btn:hover {
  background-color: red;

Here, we've set the transition-property to background-color, the transition-duration to 0.5s, and the transition-timing-function to ease-in-out. When the user hovers over the button, the background color will gradually change from blue to red over 0.5 seconds, creating a smooth hover effect.

Example 2: Expanding Element

In this example, we'll create an element that expands in width when the user hovers over it.


<div class="box">Hover Over Me</div>


.box {
  width: 100px;
  height: 50px;
  background-color: green;
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: width 1s ease-in-out;

.box:hover {
  width: 200px;

Here, we've set the transition-property to width, the transition-duration to 1s, and the transition-timing-function to ease-in-out. When the user hovers over the box, its width will gradually increase from 100px to 200px over 1 second, creating a smooth expanding effect.


CSS transitions are an essential tool for creating engaging and interactive web experiences. By understanding how to use the transition-property, transition-duration, transition-timing-function, and transition-delay properties, you can create smooth animations that enhance the user experience on your website.

Remember to experiment with different properties, durations, and timing functions to find the perfect combination for your project. And as always, practice makes perfect - the more you work with CSS transitions, the more comfortable and skilled you'll become in using them.