Macromedia Flash, or simply Flash, refers to both the Macromedia Flash Player and to a multimedia authoring program used to create content for this platform (such as games and movies). The Flash Player, developed and distributed by Adobe Systems (which bought Macromedia), is a client application available in most dominant web browsers. It features support for vector and raster graphics, a scripting language called ActionScript and bidirectional streaming of audio and video.

Strictly speaking, Macromedia Flash is the integrated development environment (IDE) and Flash Player is the virtual machine used to run the Flash files, but in colloquial language these have become mixed: "Flash" can mean either the authoring environment, the player, or the application files.Since its introduction in 1996, Flash technology has become a popular method for adding animation and interactivity to web pages; several software products, systems, and devices are able to create or display Flash. Flash is commonly used to create animations and advertisements; to design web-page elements; to add video to web sites; and, more recently, to develop Rich Internet Applications.