🎨 What Are CSS Browser Prefixes?

CSS browser prefixes are special keywords added before certain CSS properties to make them work correctly in specific browsers.

They were mainly used when browsers were testing new or experimental CSS features.

Let’s understand how they work 👇

A browser is a software application used to open and display websites.

It reads HTML, CSS, and JavaScript code and visually renders web pages on the screen.

• Google Chrome
• Mozilla Firefox
• Microsoft Edge
• Safari
• Opera
• Yandex Browser
• Internet Explorer (old)

Each browser uses its own rendering engine to process and display web content.

Not all browsers support new CSS features at the same time.

Sometimes a browser introduces a new feature as an experimental technology before it becomes an official web standard.

To support these experimental features, browsers use special prefixes.

A prefix tells the browser: “This CSS rule is specifically designed for your browser engine.”

A CSS property may behave differently across browsers.

Without prefixes:

• Some styles may not work
• Certain animations or effects may fail
• The website appearance may become inconsistent

Using prefixes helps developers create websites that look and work similarly in different browsers.

The World Wide Web Consortium (W3C) recommends writing browser prefixes in a specific order.

• -webkit-
• -moz-
• -o-
• -ms-
• -mso- (if necessary)
• Standard CSS property (without a prefix)

This ensures better browser compatibility.

/* Rounded corners example */

div {
  -webkit-border-radius: 10px; /* Chrome, Safari, Opera, Yandex */
  -moz-border-radius: 10px;    /* Firefox */
  -o-border-radius: 10px;      /* Old Opera */
  -ms-border-radius: 10px;     /* Old IE / Edge */
  border-radius: 10px;         /* Standard CSS */
}
                

💡 This allows browsers to apply the same styling consistently.

Modern browsers now support most CSS properties without prefixes.

Because of this, prefixes are used much less than before.

However, they may still be useful when:

• Supporting older browsers
• Using experimental CSS features
• Building projects requiring maximum compatibility