HTML and CSS Reference
Working with Plug-ins
HTML is very flexible for a text-based computer language, but, by itself, it can't do every-
thing. For this reason, browsers are designed to be extended through a plug-in architecture.
Plug-ins can make it possible to open non-web documents and handle other tasks typically
suited for desktop applications. Some plug-ins, like the Flash Player from Adobe, are almost
ubiquitous and have become a platform themselves. In this lesson, you learn how to work with
plug-ins in general and also, specifically, with the Flash Player to display animations and the
competing Microsoft Silverlight plug-in.
A plug-in is a small computer application that works with one or more browsers to provide
additional functionality. Plug-ins typically need to be installed separately by the user, although
in certain instances they may be included in the browser installation. Because plug-ins most
frequently require site visitors to take an extra step, the web designer must be sure their use is
important, if not essential, to the site's viability.
Web designers do not insert plug-ins into their web pages — they insert content that requires a
plug-in to be displayed in a browser. For instance, you don't add the Flash Player to your page,
you add an SWF file that relies on the Flash Player to be seen. Plug-in content comprises one
or more external files that must be published online along with the HTML source code, CSS,
images, and other files.
Two HTML tags are used for including plug-in content in a web page: <embed> and <object> .
At various times over the history of the Web, these two tags have been used both separately
and together to add plug-in material to a page. This section takes a look at the code necessary
for these tags and tag combinations starting with the <object> tag.