Most important Vendor-specific rules while working with cross browser issues.
CSS3 introduced vendor-specific rules, which offer you the possibility of writing some additional CSS applicable for only one browser.
These vendor-specific rules are intended to help us fix cross browser issues. Vendor-specific rules also provide us with early implementations of standard properties and alternative syntax. Last but not least, these rules allow browsers to implement proprietary CSS properties that would otherwise have no working standard (and may never actually become the standard).
For these reasons, vendor-specific rules play an important role in many new features of CSS3. For example, animation properties, border-radius, and box-shadow all depend on vendor-specific rules.
Vendors use the following prefixes:
• WebKit: -webkit
• Firefox: -moz
• Opera: -o
• Internet Explorer: -ms