Adobe Flash (formerly Macromedia Flash) is a multimedia platform used to add animation, video, and interactivity to Web pages. Flash is frequently used for advertisements and games. More recently, it has been positioned as a tool for "Rich Internet Applications" ("RIAs").

Flash manipulates vector and raster graphics to provide animation of text, drawings, and still images. It supports bidirectional streaming of audio and video, and it can capture user input via mouse, keyboard, microphone, and camera. Flash contains an Object-oriented language called ActionScript.

Flash content may be displayed on various computer systems and devices, using Adobe Flash Player, which is available free of charge for common Web browsers, some mobile phones and a few other electronic devices (using Flash Lite).

Flash as a format has become widespread on the desktop market; one estimate is that 95% of PCs have it, while Adobe claims that 98 percent of U.S. Web users and 99.3 percent of all Internet desktop users have installed the Flash Player, with 92 to 95% (depending on region) having the latest version. Numbers vary depending on the detection scheme and research demographics.