INTRODUCTION TO CSS3 AND MODERN WEB DESIGN - Practical CSS3: Develop and Design - page 13

GENERAL CSS3 FEATURES

To w h e t y To u r a p p e t i t e , l e t 's n To w l To To k at s To m e g e n e ra l C S S 3 fe at u re s . T h e s e fe a -
tures are grouped together because they are general features that you'll meet time
and time again throughout different chapters: They are useful in many different
circumstances.

VENDOR PREFIXES

Ve n d of r p re fi x e s a re n of t e x a c t l y s p e c i fi c C S S 3 fe a t u re s , b u t a t t h e t i m e of f t h i s w r i t i n g
(and for some time after), you'll meet them repeatedly when working with CSS3.
The reason is that many of the modules you'll be using features from aren't finished.
The idea is that before a CSS feature is completely “finished” (e.g., the spec is
not quite stable, and changes may be made before the final version), it can still be
implemented inside browsers. At this stage, browser vendors add their own ven-
dor prefix to the start of the feature and use the prefixed version. This allows each
vendor to support the feature inside its own “sandbox,” as it were, so if the spec
changes and future versions work differently, this won't result in a single property
that works differently across different browsers. As an example, CSS transitions
are currently supported across browsers with vendor prefixes. A sample block of
code might look like this:

a:link {
: ;
-webkit-transition: 1s all;
-moz-transition: 1s all;
-ms-transition: 1s all;
-o-transition: 1s all;
transition: 1s all;

}

a: hover {
: ;
}