Really simple syndication (RSS) is simply a variation of XML. RSS is a spec that defines specific nodes that are common for sending data. Typically, many blog feeds include an RSS option for users to pull down the latest information from those sites. Some of the nodes used in RSS include rss, channel, item, title, description, pubDate, link, and GUID.

Looking at our iPhone example in this chapter from the Pulling data from the Web section, we can see what a typical RSS structure entails. RSS feeds are usually easy to spot since the spec requires the root node to be named rss for it to be a true RSS file.

In some cases, some websites and services will use .rss rather than .xml; this is typically fine since most readers for RSS content will pull in the RSS data like an XML file, just like in the iPhone example.

Another form of XML is called ATOM. ATOM was another spec similar to RSS, but developed much later than RSS. Because of this, ATOM has more features than RSS: XML namespacing, specified content formats (video, or audio-specific URLs), support for internationalization, and multilanguage support, just to name a few.

ATOM does have a few different nodes compared to RSS; for instance, the root node to an RSS feed would be <rss>. ATOM's root starts with <feed>, so it's pretty easy to spot the difference. Another difference is that ATOM can also end in .atom or .xml.

For more on the RSS and ATOM spec, check out the following sites: