“Browser-based interactive multimedia” is a big deal these days. If you have no idea what “browser-based interactive multimedia” is, just visit Yahoo. Chances are every animated advertisement or announcement that surrounds (and overwhelms, to my mind) the actual content on the page is “browser-based interactive multimedia”.

Let’s dissect the term. “Browser-based” means it is presented to you via your web browser. That’s a gimme. “Interactive” means that you can click on it to be taken to another web page to maybe play a simple game, apply for a home loan, or “vote” in some meaningless poll. “Multimedia” means it’s an animated graphic that can look like a movie or cartoon and can even deliver sound.

The overwhelming majority of “browser-based interactive multimedia” is created in Adobe’s (used to be Macromedia’s) Flash format. Your browser requires a Flash plug-in to display Flash content. If you don’t have the plug-in, your browser will alert you and generally point you to the place to download and install it. Most browsers come “out of the box” with Flash plug-ins installed.

More than just banner ads are delivered via Flash. Web sites for movies almost always contain elaborate Flash animations. All the movies on YouTube are in Flash video format (.flv). Flash video files are smaller in size (I’m talking file size, in kilobytes or megabytes) than traditional QuickTime or Windows Media Video files, so they show up on your web browser page faster and play for the most part without interruption. The smaller file size yields less quality than true video, but in today’s quick-edit, music video world few really notice.

Again, Adobe’s Flash format is pervasive in providing “browser-based interactive multimedia”. But, there’s a new kid on the block.

And he’s a known bully. You guessed it – this week Microsoft introduced “Silverlight”. Silverlight is a new platform for creating and delivering “browser-based interactive multimedia”. To be able to display Silverlight content, surfers will need to download and install a small (2.5 megabyte) plug-in. I installed the plug-in on my Mac, and both my Safari and Firefox browsers were capable of displaying the Silverlight demos on the Microsoft web site.

So, how does Silverlight stack up against Flash? Right now there’s not enough content around the web to compare the two with. The few demos available on Microsoft’s web site looked just like Flash to me.