Adobe Flash Player is the universal rich client for delivering effective Adobe Flash experiences across desktops and devices.

Flash Player 9 is a lightweight, highly expressive client runtime that delivers powerful and consistent user experiences across major operating systems, browsers, mobile phones, and devices. Flash Player 9 builds on the advances in Flash Player 8 by focusing on three main areas: creating a more robust programming model, achieving standards compliance, and improving performance.

This release of Flash Player includes ActionScript 3.0, a significant update to the scripting language of the runtime that provides a familiar syntax and compelling new language features; and new Flash Player APIs, such as those for the display list, enabling greater creative control over content and applications.

You can get the firefox version from here.