Adobe Flash (formerly Macromedia Flash) is a proprietary, robust graphics animation or application development program used to create and deliver dynamic content, media (such as sound and video), and interactive applications over the web via the browser.
Many graphic artists use Flash because it gives them exact control over every part of the design, and anything can be animated and generally "jazzed up". Some application designers enjoy Flash because it lets them create applications that do not have to be refreshed or go to a new web page every time an action occurs. Flash can use embedded fonts instead of the standard fonts installed on most computers. There are many sites which forgo HTML entirely for Flash. Other sites may use Flash content combined with HTML as conservatively as gifs or jpegs would be used, but with smaller vector file sizes and the option of faster loading animations. Flash may also be used to protect content from unauthorized duplication or searching. Alternatively, small, dynamic Flash objects may be used to replace standard HTML elements (such as headers or menu links) with advanced typography not possible via regular HTML or CSS (see Scalable Inman Flash Replacement).
Flash is not a standard produced by a vendor-neutral standards organization like most of the core protocols and formats on the Internet. Flash is much more self-contained than the open HTML format as it does not integrate with web browser UI features. For example: the browsers "Back" button couldn't be used to go to a previous screen in the same Flash file, but instead a previous HTML page with a different Flash file. The browsers "Reload" button wouldn't reset just a portion of a Flash file, but instead would restart the entire Flash file as loaded when the HTML page was entered, similar to any online video. Such features would instead be included in the interface of the Flash file if needed.
Flash requires a proprietary media-playing plugin to be seen. According to a study, 98% of US Web users have the Flash Player installed. The percentage has remained fairly constant over the years; for example, a study conducted by NPD Research in 2002 showed that 97.8% of US Web users had the Flash player installed. Numbers vary depending on the detection scheme and research demographics.
Flash detractors claim that Flash websites tend to be poorly designed, and often use confusing and non-standard user-interfaces, such as the inability to scale according to the size of the web browser, or its incompatibility with common browser features such as the back button. Up until recently, search engines have been unable to index Flash objects, which has prevented sites from having their contents easily found. This is because many search engine crawlers rely on text to index websites. It is possible to specify alternate content to be displayed for browsers that do not support Flash. Using alternate content also helps search engines to understand the page, and can result in much better visibility for the page. However, the vast majority of Flash websites are not disability accessible (for screen readers, for example) or Section 508 compliant. An additional issue is that sites which commonly use alternate content for search engines to their human visitors are usually judged to be spamming search engines and are automatically banned.