Webkit is an open source web browser engine that was originated by Apple Inc. and currently powers browsers such as Google Chrome, Apple Safari, the default iOS browser, and the default Android browser.

In CSS, the -webkit- prefix is used for CSS properties that have not been officially implemented either by the W3C specifications or by web browsers in general, but are available to WebKit browsers using the prefix with the property name.
For example, the property -webkit-background-size can be used to override the size of a background image, as shown below.

.header
 {
     background-image:url(bg.jpg);
     -webkit-background size:500px 50px;
 }

Webkit dominates market because it is compatible with all browser. The prefix for all browser are different but all prefix display same.

div {
    -webkit-animation: mymove 5s infinite; /* Chrome, Safari, Opera */
    animation: mymove 5s infinite;
}