A Web widget is a mini tool—a chunk of code that people can insert in just about any Web page to perform a specific function. Usually, Web widgets are snippets of HTML. Examples:

• HTML that displays a picture on a MySpace profile
  
  
• HTML that embeds a YouTube video in a blog entry
  
  
• HTML that embeds a portion of one's calendar on a personal Web site

Experienced Web developers may question the significance of Web widgets. For them, the concept of chunks of reusable HTML doesn't seem particularly revolutionary. However, for marketers, widgets have become very important on the Web.

YouTube (www.youtube.com) is perhaps the quintessential example of the success of widgets. YouTube is a Web site that enables users to share and view online video clips. When you visit a video at the YouTube Web site, you'll find a chunk of HTML that you can copy and then paste into your blog, MySpace page, or other Web site. Visitors to your site can then watch the video without having to click over to the YouTube site. Every time someone embeds a YouTube video on a page, it serves as an advertisement for the YouTube service.

Widgets have become a phenomenon for two primary reasons.

First, blogs and social networking sites allow anyone to publish content to the Web. Most blogging platforms (such as Blogger or TypePad) enable blog owners to insert raw HTML in blog entries and profiles. MySpace and other social networking sites provide members a means of customizing their profiles by inserting snippets of HTML. Members may also insert HTML in messages and comments they post to their friends.

Consequently, people who never had any intention of developing ordinary Web sites have learned some basic HTML so they can pepper their MySpace profiles with pictures and embed YouTube videos in their blog entries. These amateur HTML programmers don't author complete Web pages and don't necessarily even compose any HTML of their own, but they do insert Web widgets in their pages. Widgets have become commonplace now that the masses have Web sites of some sort and are able to incorporate widgets in them.

Second, widgets facilitate viral marketing. If you provide a useful service or interesting content on your Web site, you can make it available as a widget by posting HTML that others can copy and paste in their pages. The content then becomes directly accessible from those pages, and it serves as an advertisement for your site. Visitors to those pages will become familiar with the service or content and may click the link to visit your site. (Widgets typically provide a link back to the site that makes the widget code available.) In some cases, they will copy the widget into their own pages. Since so many people now have basic HTML knowledge, the potential for the widget "spreading" to other pages is enormous.

An example is Dadnab (www.dadnab.com), a service that I developed to enable users to plan their trips on mass transit (buses and rail) using text messaging from their mobile phones. Dadnab recently introduced Web widgets as part of a viral marketing program. The steps in the program were as follows:

1. Develop a demo of the service so that users can try it on the Web. (You can find the demo on the front page of the Dadnab Web site.)
   
   
2. Make it so the demo can be plugged into virtually any Web page.
   
   
3. Provide visitors to the Dadnab Web site the chunk of HTML that they can plug into their pages.
   
   
4. Invite visitors to use the widget in their pages and spread the word.

The snippet of HTML is here, and you can view an example of the Dadnab Web widget on my blog.

To incorporate the power of Web widgets in your marketing programs, be creative. Consider what aspects of your product people would want to try or show off if it's presented to them as a widget in a blog or social networking site. Also consider what would make them likely to spread the widget.

For example, a widget could quiz the visitor on a topic related to your product and then assign a score. Eager to share her score with others, the visitor might embed the widget in her MySpace profile. The widget on her page would prominently display the score she received and allow others to take the same quiz.

Web widgets enable people to spread the word about services they love. If you haven't incorporated Web widgets in your marketing programs, you're missing an opportunity to unleash their viral marketing power.