Flash is a 2D animation software used widely for multimedia applications. It was launched by Macromedia in 1996, but Macromedia was acquired by Adobe in 2005. So the popularly known "Macromedia Flash" became "Adobe Flash".
Flash is based on vector graphics that enables to upload or download files very fast. Recent time's flash animations are used in ads, websites, movies, online games. It has the advanced action scripting to add perfection to the animations.
Flash animations or movies are very much compatible to all known browsers and operating systems.