These tags are only understood by a program that supports RSS, also known as an aggregator program, or a website that has been designed to display RSS feeds (such as Google's Reader). If you open an RSS file with a program that does not support it, all you will see is code. You can see an example by opening up this site at CNN.com with Internet Explorer or Mozilla Firefox (Apple's Safari web browser has a built in RSS reader that can display this file, and this feature will be included in the upcoming Internet Explorer 7).
RSS is not used with just podcasts. In fact, RSS has been used for a while to deliver news headlines by sites such as CNN. If you open the file above with an aggregator program or using the Google Reader site, you will see that the code displays a listing of CNN's top stories, each with a summary of the story and a link that allows you to read the full version. RSS feeds have also been used by blog authors (blog is short for web log or online journal) to let their readers know when the blog has been updated.
With podcasts, each individual item in the RSS code includes an additional tag that points to an audio or video file (the enclosure tag). The enclosure is similar to an attachment in email, except that the RSS file only includes pointers to the files that make up the episodes, not the files themselves.. As with email attachments, the enclosures can be a number of different types of files: audio, video, still pictures (with enhanced podcasts), and even PDF documents.
