Plug-ins make all the difference in how your WordPress site runs.
What are Plug-ins?
Short version, plug-ins are bits of code designed to extend the functionality of your site to do almost anything. WordPress itself is designed to be lean and functional out of the box, but with plug-ins you add the extra functionality you need. Everyone had different needs, so the capability to add plug-ins keeps the WordPress core code clean and uncluttered, while at the same time allowing you the flexibility to easily add on features that make your site what you need.
For example, if you want to create a podcasting site with WordPress, two plug-ins help with that task: Podpress and Powerpress. They provide similar functions. They take a link to an MP3 and add a Flash Audio player on your site to each post with an MP3 link so you can play and listen to the episode and also add a download link and other functions, such as notifying Apple iTunes that you have a new episode when you post one. With plug-ins, the possibilities for customizing your site becomes nearly endless.
If you are into SEO, you should check out my plugin RSS-to-Post. You can download a free version from WordPress.org. RSS-to-Post, take an RSS Feed and adds the entrees to your post pages, just below the content. Why? this links sites together while also providing dynamic content. Every time your feed changes every page on your website changes. Thus, causing Google to re-crawl your site. The more you can keep Google around the better.
